Figure 2.1 Aristotle’s Theory of the Rainbow (from Dales 1973, 83)
The object of sight is the visible, and what is visible is colour. . . [C]olour is what lies upon what is in itself visible; ‘in itself’ here means not that visibility is involved in the definition of what thus underlies colour, but that that substratum contains in itself the cause of visibility. Every colour has in it the power to set in movement what is actually transparent; that power constitutes its very nature. That is why it is not visible except with the help of light; it is only in light that the colour of a thing is seen.
—Aristotle, On the Soul1
In this chapter, I begin my genealogy by tracing the history of the Aristotelian strand of thought about color. It holds that color is an inherent property of objects that exists independently of light and perceivers. My goal is to make explicit some of the core commitments of this way of thinking about color, in order to show how these commitments persist in how we currently think, as well as how they lay the groundwork for the Cartesian strand’s emergence in opposition to these commitments.2 As a way of spelling out the Aristotelian strand, I draw liberally from both Aristotle’s own writings as well as from those of a number of Scholastic Aristotelians (especially those that were familiar to Descartes and his contemporaries). The Aristotelian strand is, in this sense, a composite. It combines sources in Aristotle’s own writings with lines of inheritance and development in the writings of Scholastic Aristotelians.
Generally, about all perception, we can say that a sense is what has the power of receiving into itself the sensible forms of things without the matter, in the way in which a piece of wax takes on the impress of a signet-ring without the iron or gold.
—Aristotle, On the Soul3
At the core of the Aristotelian strand is the general claim that sense organs are able to perceive objects in virtue of being able to take objects’ forms without thereby taking on their matter. This act of taking on the form of an object involves a change or alteration in the sense organ.4 Aristotle understands this change in teleological terms, as the actualization of a potentiality in the sense organ. Each sense organ has the ability to take on a specific sort of form, and the sense organs are individuated in terms of the sort of form that they have the ability to take on. The potentiality of sense organs is, in this sense, limited. As the Scholastic Aristotelian Eustachius puts it, “no faculty can escape the limits of its proper object—vision can perceive only what is visible, hearing what is audible, and so on” (Eustachius 1609/1614, in Ariew et al. [1998, 87]). Perception takes place when a sense organ’s potential to take on its characteristic sort of form is actualized.
In the rest of this chapter, I focus on the following three aspects of the Aristotelian strand of thought about color. It is these three aspects that are most directly entangled in the problem of color realism.
In dealing with each of the senses we shall have first to speak of the objects which are perceptible by each. The term ‘object of sense’ covers three kinds of objects, two kinds of which we call perceptible in themselves, while the remaining one is only incidentally perceptible. Of the first two kinds one consists of what is special to a single sense, the other of what is common to any and all of the senses. I call by the name of special object of this or that sense that which cannot be perceived by any other sense than that one and in respect of which no error is possible; in this sense colour is the special object of sight.
—Aristotle, On the Soul5
Aristotle introduces color as the proper object of vision. He has two aims in doing so.
First, he aims to introduce a distinction between color and two other types of things that we are capable of perceiving through vision, which he refers to as common and incidental objects of vision. Common objects include things like motion, which can be perceived by more than one sense ( DA II.6, 418a17–418a19). Incidental objects include things like someone’s social role, which are not directly perceived at all, but which coincide with things that are directly perceived, and can be inferred from them ( DA II.6, 418a20–418a25).
Second, he aims to use color to define vision. For Aristotle, a sense organ is functionally defined in terms of its proper object, the particular sort of quality that it alone is capable of perceiving. Vision is, in this sense, functionally defined as the eye’s ability to see color. Aristotle takes this functional definition quite literally: as he puts it, “when seeing is removed the eye is no longer an eye, except in name—no more than the eye of a statue or of a painted figure” (DA II.1, 412b20–21).6 His point is that the relationship between a sense organ and its proper object is not at all accidental or contingent; it is essential to a sense organ being the sense organ that it is that it be able to perceive its proper object. As Thomas Aquinas puts this aspect of Aristotle’s view, “the essence of each sense and its definition lies in its being naturally suited to be affected by such a sensible. For the defining account of any capacity consists in its relationship to its proper object” (Aquinas c. 1268/1951, in [Pasnau 2000, 29] [emphasis in original]).
Importantly, defining vision in terms of color is not the same thing as defining color in terms of vision or holding that the existence or nature of colors in any way depends on vision. With regard to the existence of colors, Aristotle is quite clear that they exist prior to, and independent of, vision. He states that “the perceptible seems to be prior to perception” (Cat 7, 8a6–8, trans. Ackrill) and “the destruction of the perceptible carries perception to destruction, but perception does not carry the perceptible to destruction” (Cat 7, 7b35). With regard to the specific natures of different colors, Aristotle is quite clear that colors are not defined by how they look. Rather, the nature of each color is defined by the specific mixture of ingredients that makes it up. Here is how he puts this point:
Colours will thus, too be many in number on account of the fact that the ingredients may be combined with one another in a multitude of ratios; some will be based on determinate numerical ratios, while others again will have as their basis a relation of quantitative excess. (Sens. I.3, 440b18–440b23, trans. Beare)7
For Aristotle, individual colors are defined by these ratios. As Alison Simmons summarizes this point, “[t]o be blue, for example, is not to look a certain way, but to have a certain essence and definition” (Simmons 1994, 118). These two points combine to illustrate the strong sense in which Aristotle is “an unabashed realist about objects of sense” (Broadie 1993, 137).8 Simply put, Aristotle’s realism about colors means that he does not think that the nature or existence of colors depends on being perceived; colors are what they are and exist independently of our perception of them.9
Aristotle’s realism about colors is further illustrated by his account of how the perceptual process takes place. In Myles Burnyeat’s words, the proper objects of perception “are the chief factors in the causal explanation of perception” (Burnyeat 1995b 19–20). In the case of visual perception, this process involves three factors: colors, the medium of vision, and the eye.
The visual process begins when colors cause an alteration in the medium that stands in between colors and the eye. It is this medium that then causes an alteration in the eye. Aristotle refers to this medium as the transparent, because it is something that is capable of being transparent, such as air, water, or glass. His reason for thinking that there must be such a medium is rather straightforward:
If what has colour is placed in immediate contact with the eye, it cannot be seen. Colour sets in movement what is transparent, e.g. the air, and that, extending continuously from the object of the organ, sets the latter in movement. (DA II.7, 419a12–15)
For an alteration in this medium to take place, however, the medium must be in a certain state: its potentiality to be transparent must be actualized or, more simply, it must actually be transparent.
Light, or illumination, is the actualization of the potentiality of the medium of vision to be transparent. Light is, in this sense, a state of the medium of vision. As Jean De Groot puts this point, “Aristotle treated light solely in relation to its role in visual perception” (De Groot 1991, 21). Illumination/transparency is the state of the medium of vision that makes it possible for us to see the colors of things through this medium. A helpful way of thinking about Aristotle’s conception of light is to think about how we say that children can play outside as long as it is light out.10 In a similar way to which “being light out” makes it possible for children to play outside, Aristotle thinks that “being light out” makes it possible for us to see the colors of things.
Significantly, this implies that Aristotle does not hold that color experiences are caused by light. Instead, being illuminated/transparent is the state of the medium of vision that makes it possible for colors to cause color experiences. “Being light out” is the state that the transparent medium must be in in order for it to be possible for colors to be causally efficacious. In Gary Waldman’s words, “Aristotle would, like us, say that one cannot see in the dark because there is no light, but in his theory the inability to see stems from the inability of the medium to transmit the colors of opaque bodies” (Waldman 2002, 3). Accordingly, for Aristotle, light does not play a causal role in the process of color perception. This is because light is not the sort of thing that can play a causal role. As he puts it, “light is neither fire nor any kind whatsoever of body nor an efflux from any kind of body (if it were, it would again itself be a kind of body)” (DA II.7, 418b14–17); or even more simply, “[l]ight or darkness. . . leave bodies quite unaffected” (DA II.12, 424b7–8). Simply put, Aristotle holds that colors cause color experiences, not light.
Perhaps the clearest way to appreciate how Aristotle is thinking about light here is to note that he does not think it involves any sort of motion whatsoever. As he puts it:
Empedocles (and with him all others who use the same forms of expression) was wrong in speaking of light as ‘travelling’ or being at a given moment between the earth and its envelope, its movement being unobservable by us; that view is contrary both to the clear evidence of argument and to the observed facts. (DA II.7, 418b21–24)
For Aristotle, rather than involving any form of motion, light is a state of the medium that stands in between the colors of things and our eyes, the state of it actually being transparent, such that we can see the colors of things through it. As Paul Lettinck puts this aspect of Aristotle’s view, “light is not some substance traveling from the light source to the eye or vice versa; it is not a motion, but a certain condition of the transparent, which comes about and disappears instantaneously” (Lettinck 1999, 244).
Thus, Aristotle has two related reasons for thinking that colors exist independently of vision. First, colors themselves are required for initiating the causal process that leads to visual perception; i.e., colors, not light, are the causes of visual experiences. Here is how he puts this point:
Whatever is visible is colour and colour is what lies upon what is in itself visible; ‘in itself’ here means not that visibility is involved in the definition of what thus underlies colour, but that that substratum contains in itself the cause of visibility. (DA II.7, 418a28–31)
Second, sense organs cannot, by themselves, actualize their potentiality to take on their characteristic sorts of forms; they must take on these forms from outside of themselves. For Aristotle, our ability to have experiences of red is, in this sense, dependent upon the independent existence of redness. Here is how he puts this point:
For sensation is surely not the sensation of itself, but there is something beyond the sensation, which must be prior to the sensation; for that which moves is prior in nature to that which is moved, and if they are correlative terms, this is no less the case. (Met. IV.5, 1010b30–1011a2, trans. Ross)11
Thus, Aristotle holds that just as there is a necessary connection between being an eye and being able to see colors, there is also a necessary connection between seeing colors and the independent existence of those colors, outside of the eye.
In sum: for Aristotle, color, not light, is the proper object of vision, and vision itself is functionally defined as the ability to perceive color. As he puts it, “sight is the sight of something . . . in fact it is relative to colour” (Met. V.15, 1021b1–2). Richard Sorabji nicely summarizes this aspect of Aristotle’s view when he points out that, “[o]ne description of colour [that Aristotle gives] is that it is the object of sight, but this is used to define sight, not colour” (Sorabji 2004, 129–130; see also Sorabji 1971).12
[A] species intentionalis is called here some formal sign of something which is presented to the senses. . . The species is called ‘intentional’ because the sense by means of the species reaches for the object. For example, when the eye perceives a color in the distance, the philosophers say that a certain similarity of the color itself. . . is received by the eye, i.e., a certain quality which, propagated by the color itself through the medium of air and received by the sense of sight itself, has the power to represent the color itself.
—Eustachius of Saint-Paul, A Compendium of Philosophy in Four Parts (1609)13
The doctrine of species is a central part of the Scholastic Aristotelian account of sense perception, with recognizable roots in Aristotle’s own account of the sensory process.14 Scholastic Aristotelians first started using the word “species” in their accounts of sense perception in the thirteenth century, as the result of Latin translations of Arabic translations of Aristotle’s On the Soul. “Species” is a translation of the Greek word “eidos/eidē,” meaning form, shape, or kind (Preus 2007, 96–97).15 The doctrine of species is a way of interpreting Aristotle’s claim that sense perception involves a sense organ “receiving into itself the sensible forms of things without the matter” (DA II.12, 424a18–19 [emphasis added]). Species are the Scholastic Aristotelians’ way of understanding the specific role that forms play in this process, as the causal intermediaries that stand in between an object and a sense organ and make it possible for the sense organ to perceptually represent that object.
By the early seventeenth century, the doctrine of species found widespread acceptance by Scholastic Aristotelians.16 It was endorsed in all three of the textbooks on Aristotle that Descartes studied in school, as well as the textbook by Eustachius that Descartes discovered (or possibly rediscovered) later in life and which he described as “the best book ever written” on Scholastic Aristotelian philosophy (CSM III 156).17
The doctrine of species is an elaboration of the role that Aristotle attributes to the medium in the perceptual process. As with Aristotle, the doctrine holds that sense perception begins when a sensible quality of an object alters the medium between the object and the sense organ. Species enter at the next stage, as a way of explaining how the alteration of the medium brings about the alteration of a sense organ. The doctrine holds that when a sensible quality alters the medium of perception, it produces something in the medium that resembles that quality without being identical to it. This something is a species. Once this species is produced in the medium it then multiplies, or produces further and further instances of itself, in the medium. This process of producing further and further species is repeated until it brings about an alteration in the sense organ of a perceiver. As with Aristotle, this alteration involves the sense organ taking on the form of the object of perception, without its matter. It is at this point that the sense organ perceptually represents its object.
For our purposes, the crucial thing to note about the doctrine of species is that it is a resemblance theory of perceptual representation.18 It is a resemblance theory because it holds that color experiences represent colors in virtue of resembling them. The doctrine is, in this sense, a theory about how it is that color experiences represent, are about, or refer to, anything at all.19 According to this doctrine, color experiences represent their object in virtue of sharing a form with those objects, in virtue of, in this sense, resembling the objects that they represent. Here is how Katherine Tachau summarizes this aspect of the Scholastic Aristotelian view:
[It is] precisely insofar as [species] are exact likenesses of their generating objects [that] these images are able to make their objects present to and within the percipient mind, i.e., to represent external reality. . . . [S]pecies are “natural signs (signia naturalia) of their objects. These signs can be distinguished from conventional ones established or, in Baconian terms, “imposed” (imposita) arbitrarily as are the particular significative sounds of particular languages. The distinction lies in the fact that, in contrast to those that signify conventionally (ad placitum), the relation of an intention or species to its generating object is innate, by virtue of their shared nature. (Tachau 1988, 16–18 [emphasis in original])
As Tachau’s summary brings out, the claim that color experiences represent colors in virtue of resembling them is intended to contrast with other, non-resemblance-based forms of representation. Whereas words, for instance, do not represent their objects in virtue of resembling those objects, the Scholastic Aristotelians hold that color experiences do represent their objects in virtue of resembling them. Simmons explains this aspect of the doctrine by saying that “it is their being similitudes that is supposed to account for the referential representationality of sensory experience: it is because it is a similitude of the quality which produced it that a species in my eye makes me see that quality out there” (Simmons 1994, 104–105 [emphasis in original]).20
In sum: the doctrine of species is a resemblance theory of perceptual representation, which holds that color experiences represent colors in virtue of resembling them and which thereby ensures that most color experiences accurately represent their objects.21
[I]t is not necessary for the object to be present in the manner in which it is seen, but only in the manner in which it is capable of impressing a species [on the sense organ]. When the neck of a dove appears to be multi-colored, it is not necessary that the colors be really present to the eye; it is enough that the rays of light act on the neck of the dove in such a way that it is rendered apt for causing the species of these colors. When this happens the exterior sense indeed perceives, in some fashion, an absent thing, namely, the color, for the color is not present.
—Francisco Suárez, Commentary on Aristotle’s On the Soul (1575)22
Although Aristotle and the Scholastic Aristotelians think that color experiences are by-and-large veridical, they do not think that these experiences are immune to error. As a way of explaining the possibility of perceptual error with regard to the colors of things, they introduce a distinction between true and apparent colors. This distinction is implicit in Aristotle’s Meteorology,23 becomes explicit in Posidonius’s first-century B.C.E. work in meteorology,24 and runs throughout Scholastic Aristotelian textbooks up to the early seventeenth century.25
The distinction between true and apparent colors is a particular way of thinking about what it would be for something really to be a certain color, as opposed to it merely appearing to be that color. According to this distinction, something really is a certain color if that color inheres in it.26 For example, the blueness of blue jeans is a true color, because it inheres in the jeans. By contrast, the colors we see on the shimmering iridescent necks of doves are apparent colors because they are constantly changing (or disappearing altogether). Followers of Aristotle refer to this second sort of color in many different ways: as apparent, changing, iridescent, transient, emphatical, accidental, phantastical, fugitive, or false. Running throughout all of these ways of referring to apparent colors is a common theme: whereas true colors are really there because they inhere in objects, apparent colors are mere appearances that are not really there because they are (in some sense) due to reflection.
The distinction between true and apparent colors has its origins in Aristotle’s theory of the rainbow.27 Perhaps surprisingly for many of us today, Aristotle and many of his followers think that the colors of the rainbow are apparent colors: that is, that they are mere appearances that are not really there. To see why they think this, it will help to spell out some of the specifics of Aristotle’s theory.28
According to Aristotle, when we see rainbows, we are seeing a distorted reflection of the sun, one that produces an optical illusion.29 The reflection we are seeing is off of raindrops, which function as tiny mirrors that reflect the color, but not the shape, of the sun. These tiny reflections produce an illusion in two respects. First, like all mirrors, they make it appear as if something is somewhere that it is not. In the case of rainbows, they make it appear as if the sun’s color is somewhere in the sky that it is not. The view that mirrors produce optical illusions in this manner is a mainstay of ancient and medieval optics.30 For example, in Ptolemy’s Optics, mirrors are discussed “primarily as examples of optical illusions—in them, we see objects in places where they really do not exist” (Pendergrast 2003, 64). In the same manner, Aristotle thinks that the tiny mirrors that produce the apparent colors of the rainbow make it appear as if the sun’s color is directly in front of one’s eyes, when in fact it is behind them. The second respect in which these tiny reflections produce an illusion is with regard to the particular colors we see in them, the three apparent bands of red, green, and violet they produce in the sky.31 Since the sun is not actually red, green, and violet, these colors are distorted reflections of the sun’s color, akin to the distorted colors we see in a darkened mirror.32 In sum, for Aristotle, when we see a rainbow, we are seeing a double illusion: we are seeing distorted reflections in front of us of the color of the sun behind us.
Figure 2.1 Aristotle’s Theory of the Rainbow (from Dales 1973, 83)
That Aristotle thinks individual raindrops function as darkened mirrors explains why he thinks the colors that we see in them are mere appearances, but it does not explain why we see different bands of apparent colors in the rainbow. To explain how these different apparent colors are produced, Aristotle proposes that the raindrops that produce the rainbow make up a perfect hemisphere, with the observer at its center (see Figure 2.1, below). The hemisphere has its base on the plane of the horizon, with the observer (O) in the center of this plane, the sun (S) on the hemisphere directly behind the observer, and the rainbow (E´ to E´´) directly in front.
Aristotle uses this mathematical model to explain a number of observable features of the rainbow: its three different bands of apparent color, its apparent shape and location in the sky, and why it appears to move with the observer.33 Aristotle’s explanation for how the three different bands of apparent color are produced is based on the supposition that the distance of an object from one’s eyes weakens one’s ability to see its true color. Here is how he puts this supposition:
[W]hen sight is reflected it is weakened and, as it makes dark look darker, so it makes white look less white, changing it and bringing it nearer to black. When the sight is relatively strong the change is to red; the next stage is green, and a further degree of weakness gives violet. (Meteor. III.4, 374b23–27)34
Thus, since the distance from the observer to the sun, via the raindrops, is shortest with regard to the region of the raindrops that make up the uppermost band of the rainbow, the apparent color of this region is red; since the distance from the observer to the sun is slightly further with regard to the middle band, its apparent color is green; and since the distance from the observer to the sun is even further with regard to the lowest band, its apparent color is violet. The apparent shape, location, and movement of the rainbow are all explained by the supposition that the raindrops that produce the rainbow through reflection make up a perfectly smooth hemispheric mirror. As one moves around inside this curved mirror, the apparent location of the rainbow in the sky moves with one.
For our purposes, Aristotle’s theory of the rainbow is significant because it provides us with a paradigmatic example of what it would be for something to appear to be a certain color without really being that color. Scholastic Aristotelians inherited this aspect of Aristotle’s theory of the rainbow and its associated distinction between true and apparent colors, with one modification. The modification is that, whereas Aristotle explains apparent colors in terms of the reflection of sight, Scholastic Aristotelians explain them in terms of the reflection of light.35 As Eustachius puts the underlying basis for the contrast between true and apparent colors, some “colors are only apparent, not true and fixed, because they result from the mere reflection of rays” (Eustachius 1614, 235, translated by Jake Browning and Jay Elliott). Or, as Marco Antonio de Dominis puts it,
Apart from the actual colours of the bodies remaining in the bodies themselves—no matter what is the cause of their origin—Nature has some colours which are able to change or to be altered. These are called emphatic and apparent and I [de Dominis] am accustomed to call them the bright or gleaming colours. I have no doubt that these colours are derived from light, in fact, they are nothing other than light itself. (De Dominis 1611, Chap. 3, p. 9, in Halbersma [1949, 27] [emphasis in original])
For the Scholastic Aristotelians, the distinction between true and apparent colors boils down to a distinction between two different ways in which light relates to the perception of colors: with the perception of true colors, light is involved only in the sense that the medium of vision must actually be illuminated/transparent; with the perception of merely apparent colors, by contrast, light is the cause of the experience itself. Here is how Antonio Rubio explains what is going on when we perceive the merely apparent colors of the rainbow:
[I]n the case of the rainbow the eye sees light that appears to it as red, or as some other color—not through a species of color, but through a species of light. Thus the eye sees by an act of vision which is identical to that by which the very same object would be seen if there were no deception. (Rubio 1621, 394, in Hoffman [1996, 367–368], which is revised from Clemenson [2001, 121–122])
It is crucial to note the echo of Aristotle in Rubio’s claim that this appearance is deceptive: the apparent colors of the rainbow (or other apparent colors) are optical illusions because they result from nothing more than reflection.
In sum: the distinction between true and apparent colors is a prominent and influential way of drawing a reality/appearance distinction with regard to color experiences. According to this distinction, an object really is the color it appears to be if that color inheres in the object itself, independently of light. An object only appears to be a certain color if that apparent color depends upon light. With experiences of true colors, light is necessary to see them, but the colors themselves exist independently of light. With apparent colors, their very existence depends upon light.
The distinction between light and color was universal in early optical thought. . . [I]n Aristotle’s scheme light is not itself visible, but signifies a state of the medium that makes colored bodies on the other side of it visible; color, rather than light, is the “proper object” of sight.
—David C. Lindberg, “The Science of Optics: Science in the Middle Ages” (1978)36
At the core of the Aristotelian strand of thought about color is a particular way of thinking about the relationship between color, light, and vision. According to this way of thinking, light makes it possible for us to see the colors of things, but the colors of things are themselves independent of light and perceivers. As a way of demonstrating the persistence of the Aristotelian strand in how we think about color, consider the following two intuition pumps.37
There is a completely dark, windowless closet in your apartment. Sitting on the floor of your closet is a perfectly normal rubber basketball that you never use, because you are a lazy bastard. When you open the door of the closet and turn on the overhead light, the basketball looks orange, just like other rubber basketballs.
Ask yourself the following questions:
Q1: Does turning on the overhead light change anything about the basketball?
Q2: When you turn on the overhead light and look down at the color of the basketball on the floor, are you thereby seeing the light from the overhead light?
In response to Q1, I am inclined to say that turning on the overhead light does not change anything about the basketball. All that it does is make it possible for me to see the color of the basketball, which is something that is there anyway, regardless of whether the light is turned on or off or whether I am looking at it or not. In response to Q2, I am inclined to say that when I turn on the overhead light and look at the basketball, I am not seeing the light from the overhead light. I am just seeing the color of the basketball.
If you share these inclinations, then that attests to the presence of the Aristotelian strand in how we think about the relationship between color, light, and vision. We both think that light merely makes it possible for us to see the colors of things. Furthermore, when we look at the colors of things in the light, we are seeing only the colors of things, not the light itself. Colors, in this sense, exist independently of light.
You are a professional truck driver. You are making a delivery that involves backing your truck down a narrow alley up to a loading dock. In order to see what is behind the truck, you must rely entirely on your side view mirrors. Doing so, you are surprised to see that someone standing on the dock is wearing a Santa Claus suit on top of a Chewbacca costume.
Ask yourself the following questions:
Q3: Is the redness that you are seeing a property of the Santa Claus suit? Is it a property of the side view mirror?
Q4: Do you think the Santa Claus suit will continue to be the same color in the dark that it is in the light? Will the mirror be the same color in the dark that it is in the light?
Q5: Do you think that the Santa Claus suit will continue to be the same color if you change your line of sight on it? Will the mirror continue to be the same color if you change your line of sight on it?
In response to Q3, I am inclined to say that the redness I am seeing is a property of the Santa Claus suit, but not the mirror. The redness of the suit is merely reflected by the mirror. With Q4, I am inclined to say that the Santa Claus suit will continue to be red in the dark, but the mirror will not continue to be the same color. With Q5, I am inclined to say that the Santa Claus suit will continue to be red even if I change my line of sight, but that the mirror will not continue to be the same color.
Once again, if you share these inclinations, then that equally well attests to the continuing presence of the Aristotelian strand in how we think about color, because they imply that there is a fundamental difference between the true redness of the Santa Claus suit, and the merely apparent “redness” of the mirror, in terms of how each relates to light and perceivers. True colors, in this sense, are thought of as independent of light and perceivers.
For evidence that the Aristotelian strand plays a role in contemporary philosophical debates about color, we need look no further than Mark Johnston’s “How to Speak of the Colors” (1992). In this influential essay, Johnston tries to articulate some of our “core beliefs” about color, beliefs that he thinks define what it is to think about color at all. Here is one such belief (introduced in the previous chapter):
A basic phenomenological fact is that we see most of the colors of things as “steady” features of those things, in the sense of features which do not alter as the light alters and as the observer changes position. . . . A course of experience as of the steady colors is a course of experience as of light-independent and observer-independent properties, properties simply made evident to appropriately placed perceivers by adequate lighting. Contrast the highlights: a course of experience as of the highlights reveals their relational nature. They change as the observer changes position relative to the light source. They darken markedly as the light source darkens. With sufficiently dim light they disappear while the ordinary [i.e., “steady”] colors remain. They wear their light- and observer-dependent natures on their face. Thus there is some truth in the oft-made suggestion that (steady) colors don’t look like dispositions; to which the natural reply is “Just how would they have to look if they were to look like dispositions?”; to which the correct response is that they would have to look like colored highlights or better, like shifting, unsteady colors, e.g., the swirling evanescent colors that one sees on the back of compact discs. (Johnston 1992, 226–227)
In this passage, Johnston introduces a distinction between our experience of “steady” and “unsteady” colors. Johnston claims that steady colors are experienced as existing independently of light and perceivers, whereas unsteady colors are experienced as relational, insofar as “[t]hey change as the observer changes position relative to the light source.” Johnston’s distinction between steady and unsteady colors perfectly parallels the Aristotelian distinction between true and apparent colors. This parallel is perhaps most evident in the example that Johnston uses as an illustration of unsteady colors: namely, the shifting unsteady colors on the back of compact discs. His example of these unsteady colors plays exactly the same role that rainbow colors and the colors on the necks of doves play in the Aristotelian account. In both cases, this sort of example is introduced to bring out a contrast between these apparent colors and the true colors of things, which are thought to exist independently of light and perceivers. His invocation of this example in this context is vivid evidence of the Aristotelian strand’s presence in contemporary philosophical debates about color.
1. Arist. DA II.7, 418a26–418b2, trans. Smith.
2. The approach that I take in this book to the history of philosophy and science is idiosyncratic, to say the least. On the one hand, I aim to give a fairly detailed account of some of the specific contributions that Aristotle, Descartes, and their followers have made to how we think about the relationship between light and vision. On the other hand, this account is intended to serve a philosophical function: it is introduced to disentangle the different strands of thought that are intertwined in how we currently think about color, as a step towards showing how the problem of color realism rests upon this entanglement. Given that my historical account has this philosophical function, there are many aspects of Aristotle’s, Descartes’s, and their followers’ views that I do not discuss in any detail. (Most prominently, perhaps, are their contributions to the debate between intromissionist and extramissionist theories of vision.) Furthermore, there are many important exegetical debates about how, exactly, we should read specific aspects of Aristotle’s, Descartes’s, and their followers’ texts that I bracket. My decision not to discuss certain aspects of their views, as well as to bracket certain exegetical debates, is deliberate. I think that if a comparatively small number of historical considerations are highlighted, we will be better situated to see how these specific considerations are entangled in the problem of color realism.
3. Arist. DA II.12, 424a18–21.
4. There is an enormous interpretative debate about how to understand the precise sense in which Aristotle thinks that sense organs take on the forms of the objects they perceive. So-called Literalists think that the sense organ literally comes to have the same qualities as the objects perceived (Slakey 1961; Sorabji 1971, 1972, and 2004; Sisko 1996; Everson 1997). So-called Spiritualists think that this claim should be understood analogically and need not involve any material change (Broadie 1993; Burnyeat 1995a; Witt 1995; Johanson 1997; Esfeld 2000; Murphy 2005). Advocates of a middle-ground (or so-called Broad Church) reading think that perception involves a material change, but one in which the sense organ comes to resemble the object of perception without literally taking on the same quality as it (Lear 1988; Ward 1988; Silverman 1989; Granger 1990 and 1992; Price 1996; Bradshaw 1997; Magee 2000; Caston 2004; Bolton 2005; Lorenz 2008). This book brackets this interpretative debate.
5. Arist. DA II.6, 418a7–14.
6. For discussion of some of the perplexing consequences of this aspect of Aristotle’s hylomorphism, see Ackrill (1972/73). Meyering (1989, 40–45) argues that the continuing influence of this aspect of Aristotle’s view explains why the retinal image was almost universally ignored until Kepler’s pioneering work. As Meyering points out, even in al-Haytham’s (Alhazen) otherwise pioneering account of the visual process, “only the living eye is sensitive to the forms of light and color from the visible object” (Meyering 1989, 41) and any invocations of mechanical forms of image production (such as in a camera obscura) are not intended as literal descriptions of any part of the visual process.
7. Aristotle does not specify what ingredients he is referring to here. Richard Sorabji argues that these ingredients are Aristotle’s four basic elements. As he puts it, “[t]he obvious mixture for [Aristotle] to be referring to is the mixture of the four elements, earth, air, fire, and water, which he describes at such length in the De Generatione et Corruptione. All compound bodies are produced ultimately through the mixture of these elements” (Sorabji 1971, 293).
8. For similar claims about Aristotle’s perceptual realism about colors, see also Silverman (1989, 280); Burnyeat (1995b, 19–20); Everson (1995, 271) and (1997, 126–127); Broakes (1999, 72–80); Code (2008, 12).
9. Broackes (1999) is an insightful discussion of this aspect of Aristotle’s thought about color.
10. I owe this helpful analogy to Jake Browning.
11. Here is Celia Wolf-Devine’s helpful elaboration of this idea: “Our senses must be understood as in potency relative to their objects and can sense only when acted on by those objects, just as the combustible requires the presence of something from outside to make it burn. Otherwise we could sense things at will, which we cannot do” (Wolf-Devine 1993, 12).
12. Here is how Hamlyn and Pasnau make this same point: “[For Aristotle, the] relation between the sense and its object is an essential one. . . That is to say that if we use the sense we must perceive the kind of object in question, since the sense is defined by reference to the kind of object” (Hamlyn 1968, 105). “[T]he proper sensibles are special because of how they make an impression on our senses. Our senses are designed so as to be well suited to detect such objects, and so it is appropriate to define and distinguish those senses in terms of the different objects they are suited to detect” (Pasnau 2000, 30).
13. Eustachius (1609/1614, III 330), in Van Hoorn (1972, 165).
14. For a clear overview of the doctrine of species, see Hatfield (1998) and Simmons (1999, 527–530). For a history of the development of the doctrine, see Lindberg (1976), Tachau (1988), and Spruit (1994). For a detailed account of the doctrine as it was held by the Scholastic Aristotelians of Descartes’s time, see Simmons (1994). For a debate on whether the notion of species is a proper reading of Aristotle by his followers, see Burnyeat (1995a and 1995b) and Sorabji (1995).
15. There is, in this sense, a (merely) terminological similarity between Scholastic Aristotelian accounts of vision and those of ancient atomists, such as Empedocles and Democritus, who explained vision in terms of eidola or images that constantly streamed off of objects and flowed to perceivers. For an overview of ancient atomist theories of vision, see Siegel (1959), O’Brien (1970), and Lindberg (1976). For a summary of Aristotle’s and his followers’ criticisms of these theories see Avotins (1980).
16. A caveat is in order: at least 6,653 book-length commentaries on Aristotle were published between 1500 and 1650 (Blum 1988, 141–148). Unsurprisingly, these commentaries are not in complete agreement on the nature of sense perception. The aim of this section on the doctrine of species is to identify, as far as is possible, general points of agreement in the Aristotelian textbooks that were familiar to Descartes. These general points of agreement should not be taken to imply that these textbooks are in complete agreement in all details, or even that everyone writing on Aristotle accepted the doctrine of species. From the very inception of the doctrine of species, there were many critics. For example, Durandus of Saint-Pourçain and William of Ockham were notable dissenters early in the tradition (for discussion of these debates, see Lindberg [1976] and Kraml [2006]). That said, Descartes himself seems to have thought that the differences between Scholastic Aristotelians are mostly superficial, and that he was arguing against aspects of their thought that are shared by all of them. Here is how he puts this point in a letter to Mersenne:
I do not think that the diversity of the opinions of the scholastics makes their philosophy difficult to refute. It is easy to overturn the foundations on which they all agree, and once that has been done, all their disagreements over detail will seem foolish. (CSM III 156)
17. In his letters, Descartes mentions studying textbooks on Aristotle by the Coimbrian Commentators, Toletus, and Rubio (CSM III 148). He also mentions discovering Eustachius (CSM III 160) . Hatfield (1998, 956) notes that all four of these authors subscribed to the doctrine of species. For a summary of the sort of Aristotelian education that Descartes received at La Flèche, see Garber (1992, 5–9) and Gaukroger (1995, 51–61). For a summary of Descartes’s discovery of Eustachius, see Gaukroger (2002, 32–35) and Edwards (2012, 89–90). For a general account of Descartes’s engagement with Scholastic Aristotelianism, see Ariew (1999 and 2011). For a general overview of the Scholastic Aristotelian textbook tradition, see Schmitt (1988). For a general overview of Scholastic Aristotelianism in the seventeenth century, see Ariew (1998) and Ariew and Gabbey (1998). For a useful reminder of how reading the Scholastics through their critics can grossly distort some of the subtleties of their positions, see Edwards (2007).
18. It is worth noting that all of the Scholastic Aristotelians of Descartes’s time took species to be material forms, unlike many earlier advocates of the doctrine, who took them to be, in some sense, immaterial. This aspect of the history of Scholastic Aristotelian thought is clearly summarized in Gilson (1930, 20–30); Van Hoorn (1972, 164–168); Simmons (1994, 91–103). The early seventeenth-century consensus on the materiality of species is well indicated by Antonio Rubio’s straightforward assertion that “sensible species have corporeal and not spiritual being” (Rubio 1621, 326, in Simmons 1994, 94).
19. For a clear overview of theories of perceptual representation, see Cummins (1991).
20. Here is Gary Hatfield’s gloss on this same point: “[according to the doctrine of species] a kind of identity arises between the sensory power and the object sensed, which identity permits the power to be ‘directed toward’ or ‘attentive of’ the object, and so to cognise it” (Hatfield 1998, 956).
21. Here is Stuart Clark’s useful summary of this aspect of the doctrine of species: “All the metaphors associated with this process of visual cognition, notably those of mirroring, painting, and the making of impressions in wax, evoke an expectation of representational accuracy. They suggest that the doctrine of visible species was supposed to guarantee visual certainty, give or take the various errors or ‘fallacies’ of vision that were described and explained away in the textbooks on cognition, optics, and ophthalmology. Broadly speaking, the mind had direct access to accurate pictures of the world; the world was what it appeared visually to be” (Clark 2007, 1–2).
22. Suárez (1575/1978, 522–524), in Clemenson (2000, 36).
23. Although commentators on Aristotle commonly take the distinction between true and apparent colors to have its roots in Aristotle’s Meteorology, Aristotle himself does not explicitly introduce and defend any such distinction in that text (or anywhere else in his extant corpus). In the rest of this section, I spell out how the theory of the rainbow that Aristotle introduces in the Meteorology implicitly introduces this distinction. For those interested in the Aristotelian roots of this distinction, however, it is worth noting a comment that Aristotle makes in his debate with Hippocrates and Aeschylus about the color of comets. Hippocrates and Aeschylus thought that the colors of halos and comets are both due to reflection. Aristotle denies that both of these colors are similar, holding instead that “the colour of the halo is due to reflection, whereas in the case of comets the colour is something that appears actually on them” (Meteor. I.7, 344b7–8, trans. Webster). This is as close as I have been able to find of an instance of Aristotle explicitly invoking a distinction between (merely apparent) colors that are due to reflection and (true) colors that inhere in objects. For general histories of the reception of Aristotle’s meteorological writings, see Taub (2003); Heidarzadeh (2008); Martin (2011).
24. The full text of Posidonius’s work in meteorology has been lost, so our only evidence that he articulated and defended the distinction between true and apparent colors is due to Seneca (1963/1971), who argues against Posidonius’s claim that rainbow colors are illusory. For a collection of the extant fragments from Posidonius, see Kidd (1999).
25. For discussion of the history of the true/apparent distinction, see Halbertsma (1949, 22–27); Westfall (1962); Shapiro (1984, 3–5); Guerlac (1986); Boyer (1987, 53); Shea (1991, 211–212); Kemp (1990, 264); Hoffman (1996); Lee and Fraser (2001, 210–211); Crone (1999); Clemenson (2000); Werrett (2001, 143); Atherton (2004, 35–36); Gal and Chen-Morris (2010, 195–196); Darrigol (2012).
26. For Aristotle, the true colors of objects inhere in them in the strong sense that they are the direct result of the mixture of those objects’ ingredients. As he puts it, “when bodies are mixed their colours also are necessarily mixed at the same time; and that this is the real cause determining the existence of a plurality of colours—not superposition or juxtaposition. For when bodies are thus mixed, their resultant colour presents itself as one and the same at all distances alike; not varying as it is seen nearer or farther away” (Sens. I.3, 440b12–17).
27. Here is how Philoponus puts the origins of this distinction: “Aristotle. . . teaches us that some of the processes have substance and are really such as they appear. . . while others are only apparent and are due to optical illusion without being in reality such as they appear, e.g., the rainbow, the halo, rods, mock suns and similar things” Philoponus (2011, 29–30). For general histories of rainbow studies, see Boyer (1987) and Lee and Fraser (2001). For a specific focus on ancient studies, see Sayili (1939), Taub (2003), Johnson (2009), and Stothers (2009). For a focus on seventeenth-century studies, see Sabra (1981).
28. One significant aspect of Aristotle’s theory of the rainbow that I do not discuss in the main body of the text is the way in which it seems to rest upon a fundamentally different theory of vision than the one offered in On the Soul and Sense and Sensibilia. The difference is that whereas in On the Soul and Sense and Sensibilia Aristotle argues for an intromissionist theory of vision, in the Meteorology he appears to be presupposing an extramissionist theory. This apparent discrepancy has been noted by many commentators on Aristotle, at least as far back as Alexander of Aphrodisias in the third century C.E. Aristotle himself might have been unworried by this discrepancy, insofar as in Generation of Animals he says that “it makes no difference whether we say, as some do, that seeing is caused by the sight going forth from the eye. . . or whether we say that seeing is due to the movement coming from the objects” (GA V.I, 780b33–37, trans. Platt). However, given that the primary cases of vision perception that he discusses in the Meteorology involve optical illusions, there might be a possible explanation for this apparent discrepancy. Perhaps his extramissionist-sounding comments in the Meteorology are more of an attempt to differentiate cases of perceptual error from cases of veridical perception than they are an abandonment of his commitment to an intromissionist theory of vision. For general discussion of why Aristotle might have adopted these two different theories of vision in these two different contexts, see Lindberg (1976, 217 fn. 39) and Johnson (2009, 340–343).
29. For discussion of Aristotle’s theory of the rainbow, see Sayili (1939), Dales (1973, 81–92), Boyer (1987, 37–55), Smith (1999, 149–153), Lee and Fraser (2001, 105–109), Stothers (2009, 30–31), and Wilson (2013, 236–270).
30. For a useful overview history of mirrors, see Gregory (1997, 47–65). For an overview history of philosophers’ views on mirrors, see Pendergrast (2003). Here is how David Lindberg summarizes the significance of the theoretical connection that Aristotle draws between rainbows and mirrors: “Aristotle’s theory of the rainbow leads to a discussion of mirrors, [which] raises what was to become one of the central questions of the science of mirrors [in the ancient and medieval worlds]—whether the image observed in a mirror has an objective existence there or is merely the object itself perceived outside its true place” (Lindberg 1976, 87).
31. Aristotle also thinks that we sometimes see a fourth apparent color in the rainbow, yellow, but that this appearance is even more of an illusion than the other three apparent colors, since it is the result of simultaneous color contrast. As he puts it, “[t]he appearance of yellow [between the red and green bands] is due to contrast; for the red is whitened by its juxtaposition with green” (Meteor. III.4, 375a13–14).
32. Since the mirrors of Aristotle’s time were darker than the mirrors we are familiar with today, this would have been a much more familiar phenomenon for him than it is for us. The Greeks did not have silver-backed glass mirrors; they used highly polished pieces of bronze, silver, and gold as reflective surfaces. See Gulick (1902, 132).
33. Aristotle was not the first to note that the rainbow moves with the observer, nor the first to think that this movement impugned its reality. An associate of Plato’s, Philip, had already noted this, and also used it to argue that rainbows are produced in the same manner as mirror images (which also move with the observer). See Boyer (1987, 37).
34. This is a good example of Aristotle’s apparent commitment to an extramissionist theory of vision, insofar as he explains the optical illusion involved in seeing rainbow colors in terms of sight being weakened by reflection.
35. Once again, this is connected up with the question of Aristotle’s apparent commitment to an extramissionist theory of vision in the Meteorology.
36. Lindberg (1978, 356).
37. The phrase “intuition pump” is due to Dennett (1988), although I use the phrase in a slightly different sense than Dennett himself.
Ackrill, John Lloyd. “Aristotle’s Definitions of Psuchê.” Proceedings of the Aristotelian Society 73 (1972/73): 1991–1933.
Ariew, Roger. “Aristotelianism in the 17th Century.” In Routledge Encyclopedia of Philosophy Volume 1, edited by Edward Craig, 386–393. London: Routledge, 1998.
—. Descartes and the Last Scholastics. Ithaca: Cornell University Press, 1999.
—. Descartes among the Scholastics. Leiden: Brill, 2011.
Ariew, Roger and Alan Gabbey. “The Scholastic Background.” In The Cambridge History of Seventeenth-Century Philosophy, edited by Daniel Garber and Michael Ayers, 425–453. Cambridge: Cambridge University Press, 1998.
Aristotle. The Complete Works of Aristotle, edited by J. Barnes. Princeton: Princeton University Press, 1984.
Atherton, Margaret. “ ‘Green Is Like Bread’: The Nature of Descartes’ Account of Color Perception.” In Perception and Reality: From Descartes to the Present, edited by Ralph Schumacher, 27–42. Paderborn: Mentis, 2004.
Avotins, Ivar. “Alexander of Aphrodisias on Vision in the Atomists.” The Classical Quarterly, New Series, 30 no. 2 (1980): 429–454.
Blum, P. R. “Der Standardkursus der katholischen Schulphilosophie im 17. Jahrhundert.” In Aristotelismus und Renaissance–In memoriam Charles B. Schmitt, 127–148, eds. Keßler, Ch. H. Lohr & W. Sparn, Wiesbaden: Otto Harassowitz, 1988.
Bolton, Robert. “Perception Naturalized in Aristotle’s De anima .” In Metaphysics, Soul, and Ethics in Ancient Thought: Themes from the Work of Richard Sorabji, edited by Ricardo Salles, 209–244. Oxford: Clarendon, 2005.
Boyer, Carl. The Rainbow: From Myth to Mathematics. 2nd ed. Princeton: Princeton University Press, 1987.
Bradshaw, David. “Aristotle on Perception: The Dual-Logos Theory.” Apeiron 30, no. 2 (1997): 143–162.
Broackes, Justin. “Aristotle, Objectivity and Perception.” Oxford Studies in Ancient Philosophy 17 (1999): 57–113.
Broadie, Sarah. “Aristotle’s Perceptual Realism.” The Southern Journal of Philosophy 31 (1993): 137–159.
Burnyeat, Miles. “Is an Aristotelian Philosophy of Mind Still Credible? (A Draft).” In Essays on Aristotle’s De anima, edited by Martha Nussbaum and Amélie O. Rorty, 15–26. Oxford: Clarendon Press, 1995a.
—. “How Much Happens When Aristotle Sees Red and Hears Middle C? Remarks on De anima 2.7–8.” In Essays on Aristotle’s De anima, edited by Martha Nussbaum and Amelie O. Rorty, 421–434. Oxford: Clarendon Press, 1995b.
Caston, Victor. “The Spirit and the Letter: Aristotle on Perception.” In Metaphysics, Soul, and Ethics in Ancient Thought: Themes from the Work of Richard Sorabji, edited by Ricardo Salles, 245–320. Oxford: Oxford University Press, 2004.
Clark, Stuart. Vanities of the Eye: Vision in Early Modern European Culture. Oxford: Oxford University Press, 2007.
Clemenson, David. Species, Ideas and Idealism: The Scholastic and Cartesian Background of Berkeley’s Master Argument. PhD dissertation, Rice University, 2000.
Clemenson, D.L. Species, ideas and idealism: The scholastic and Cartesian background of Berkeley’s master argument. Diss. Rice University, 2001.
Code, Alan. “Aristotelian Colors as Causes.” In Festschrift for Julius Moravcsik, edited by Dagfinn Follesdall and John Woods, 235–242. London: College Publications, 2008.
Crone, Robert. A History of Color: The Evolution of Theories of Light and Color. Dordrecht: Kluwer, 1999.
Cummins, Robert. Meaning and Mental Representation. Cambridge, MA: Bradford Books, 1991.
Dales, Richard. The Scientific Achievement of the Middle Ages. Philadelphia: University of Pennsylvania, 1973.
Darrigol, Oliver. A History of Optics from Greek Antiquity to the Nineteenth Century. Oxford: Oxford University Press, 2012.
De Dominis, Antonius. De radiis visus et lucia in vitris perspectivis et iride. Venice, 1611.
De Groot, Jean. Aristotle and Philoponus on Light. New York: Garland Publishing, 1991.
Dennett, Daniel. “Quining Qualia.” In Consciousness in Modern Science, edited by A.J. Marcel and E. Bisiach, 42–77. Oxford: Oxford University Press, 1988.
Descartes. The Philosophical Writings of Descartes. 3 volumes. Translated by John Cottingham, Robert Stoothoff, and Dugald Murdoch. Volume 3 including Anthony Kenny. Cambridge: Cambridge University Press, 1988. [Abbreviated as CSM.]
Edwards, Michael. “Aristotelianism, Descartes, and Hobbes.” Historical Journal 50, no. 2 (2007): 449–464.
—. “Philosophy, Early Modern Intellectual History, and the History of Philosophy.” In The Pursuit of Philosophy: Some Cambridge Perspectives, edited by Alexis Papzoglou, 81–94. West Sussez: Wiley-Blackwell, 2012.
Esfeld, Michael. “Aristotle’s Direct Realism in ‘De Anima.’” The Review of Metaphysics 54, no. 2 (2000): 321–336.
Eustachius a Sancto Paulo. Summa philosophiae quadripartita: de rebus dialecticis, moralibus, phisicis, & metaphysicis. Paris, 1609/1614.
Everson, Stephen . “Proper Sensibles and kath'hauta Causes.” Phronesis 40 (1995): 265–292.
—. Aristotle on Perception. Oxford: Oxford University Press, 1997.
Gal, Olfer and Raz Chen-Morris. “Baroque Optics and the Disappearance of the Observer: From Kepler’s Optics to Descartes’ Doubt.” Journal of the History of Ideas 71, no. 2 (2010): 191–217.
Garber, Daniel. Descartes’ Metaphysical Physics. Chicago: University of Chicago Press, 1992.
Gaukroger, Stephen. Descartes: An Intellectual Biography. Oxford: Oxford University Press, 1995.
—. Descartes’ System of Natural Philosophy. Cambridge: Cambridge University Press, 2002.
Gilson, Etienne. Études sur le rôle de la pensée médiévale dans la formation du système cartésien. Paris: J. Vrin, 1930.
Granger, Herbart. “Aristotle and the Functionalist Debate.” Apeiron 23, no. 1 (1990): 27–50.
—. “Aristotle and Perceptual Realism.” The Southern Journal of Philosophy 31 (1993): 161–171.
Gregory, Richard. Mirrors in Mind. Oxford: Spektrurn/New York: W. H. Freeman, 1997.
Guerlac, Henry. “Can There Be Colors in the Dark? Physical Color Theory Before Newton.” Journal of the History of Ideas 47, no. 1 (1986): 3–20.
Gulick, Charles. The Life of the Ancient Greeks: With Special Reference to Athens. New York: D. Appleton and Company, 1902.
Halbertsma, K.T.A. A History of the Theory of Colour. Amsterdam: Swets & Zeitlinger, 1949.
Hamlyn, David. “Koine Aesthesis.” Monist 52 (1968): 195–209.
Hatfield, Gary. “The Cognitive Faculties.” In The Cambridge History of Seventeenth-Century Philosophy. 2 Volumes, edited by Daniel Garber and Michael Ayers, ii, 954–961. Cambridge: Cambridge University Press, 1998.
Heidarzadeh, Tofigh. A History of Physical Theories of Comets, from Aristotle to Whipple. Dordrecht: Springer, 2008.
Hoffman, Paul. “Descartes on Misrepresentation.” Journal of the History of Philosophy 34 (1996): 357–381.
Johanson, T.K. Aristotle on the Sense-Organs. Cambridge: Cambridge University Press, 1997.
Johnson, Monte. “The Aristotelian Explanation of the Halo.” Apeiron 42 (2009): 235–358.
Johnston, Mark. “How to Speak of the Colors.” Philosophical Studies 68 (1992): 221–263.
Kemp, Martin. The Science of Art: Optical Themes in Western Art from Brunelleschi to Seurat. New Haven: Yale University Press, 1990.
Kidd, Ian. Posidonius: The Translation of the Fragments, Volume III. Cambridge: Cambridge, 1999.
Kraml, Hans. “Why Did Ockham Reject Species?” In Intellect and Imagination in Medieval Philosophy, edited by M.C. Pacheco and J. Meirinhos, 1547–1554. Turnhout: Turnhout Brepols, 2006.
Lear, Jonathan. Aristotle: The Desire to Understand. Cambridge: Cambridge University Press, 1988.
Lee, Raymond and Alistair Fraser. The Rainbow Bridge: Rainbows in Art, Myth, and Science. University Park: Penn State Press, 2001.
Lettinck, Paul. Aristotle’s Meteorology and Its Reception in the Arab World with an Edition and Translation of Ibn Suwar’s Treatise on Meteorological Phenomena and Ibn Bajja’s Commentary on the Meteorology. Leiden/Boston/Koln: Brill, 1999.
Lindberg, David. Theories of Vision from al-Kindi to Kepler. Chicago: University of Chicago Press, 1976.
Lindberg, David, “The Science of Optics.” In Science in the Middle Ages, 338–68, ed. David C. Lindberg, Chicago: University of Chicago Press, 1978.
Lorenz, Hendrik. “The Assimilation of Sense to Sense-Object in Aristotle.” Oxford Studies in Ancient Philosophy 33 (2008): 179–220.
Magee, Joseph. “Sense Organs and the Activity of Sensation in Aristotle.” Phronesis: A Journal for Ancient Philosophy 45, no. 4 (2000): 306–330.
Martin, Craig. Renaissance Meteorology: Pomponazzi to Descartes. Baltimore: Johns Hopkins University Press, 2011.
Meyering, Theo. Historical Roots of Cognitive Science. Boston: Kluwer, 1989.
Murphy, Damian. “Aristotle on Why Plants Cannot Perceive.” Oxford Studies in Ancient Philosophy 29 (2005): 295–339.
O’Brien, Denis. “The Effect of a Simile: Empedocles’ Theories of Seeing.” Journal of Hellenic Studies 90 (1970): 140–179.
Pasnau, Robert. “Sensible Qualities: The Case of Sound . ” Journal of the History of Philosophy 38, no. 1 (2000): 27–40.
Pendergrast, Mark. Mirror Mirror: A History of the Human Love Affair with Reflection. New York: Basic Books, 2003.
Philoponus. On Aristotle Meteorology 1.1–3. Translation with introduction and commentary by Inna Kupreeva. London: Bristol Classical Press, 2011.
Preus, Anthony. Historical Dictionary of Ancient Greek Philosophy. Maryland: Scarecrow Press, 2007.
Price, A.W. “Aristotelian Perceptions.” Proceedings of the Boston Area Colloquium in Ancient Philosophy 12 (1996): 285–309.
Rubio, Antonio. Commentarii in libros Aristotelis De Anima. Colonia Agrippina, 1621.
Sabra, A.I. Theories of Light from Descartes to Newton. Cambridge: Cambridge University Press Archive, 1981.
Sayili, Aydin. “The Aristotelian Explanation of the Rainbow.” Isis 30, no. 1 (1939): 65–83.
Schmitt, Charles. “The Rise of the Philosophical Textbook.” In The Cambridge History of Renaissance Philosophy, edited by Charles Schmitt and Quentin Skinner, 792–804. Cambridge: Cambridge, University Press, 1988.
Seneca. Naturales Quaestiones, Books 1–3. Translated by Thomas Corcoran. Cambridge, MA: Loeb Classical Library, 1963/1971.
Shapiro, Alan E. (Editor). The Optical Papers of Isaac Newton. Volume 1. The Optical Lectures, 1670–1672. Cambridge: Cambridge University Press, 1984.
Shea, William R. The Magic of Numbers and Motion: The Scientific Career of René Descartes. Canton, MA: Science History Publications, 1991.
Siegel, R.E. “Theories of vision and color perception of Empedocles and Democritus; some similarities to the modern approach.” Bulletin of the History of Medicine XXXIII (1959): 14–159.
Silverman, Allan. “Color and Color-Perception in Aristotle’s ‘De Anima.’” Ancient Philosophy 9 (1989): 271–292.
Simmons, Alison. “Making Sense: The Problem of Phenomenal Qualities in Late Scholastic Aristotelianism and Descartes.” PhD Dissertation, University of Pennsylvania, 1994.
—. “Jesuit Aristotelian Education.” In The Jesuits: Culture, Learning and the Arts, 1540–1773, edited by J.W. O’Malley, S.J. Gauvin Alexander Bailey, Steven J. Harris, and T. Frank Kennedy, 522–537. Toronto: Toronto University Press, 1999.
Sisko, John. “Material Alteration and Cognitive Activity in Aristotle’s ‘De Anima.’” Phronesis 41, no. 2 (1996): 138–157.
Slakey, Thomas. “Aristotle on Sense Perception.” The Philosophical Review 70, no. 4 (1961): 470–484.
Smith, A. Mark. Ptolemy and the Foundations of Ancient Mathematical Optics: A Source Based Guided Study. Philadelphia: American Philosophical Society, 1999.
Sorabji, Richard. “Aristotle on Demarcating the Five Senses.” The Philosophical Review 80, no. 1 (1971): 55–79.
—. “Aristotle, Mathematics, and Colour.” The Classical Quarterly 22, no. 2 (1972): 293–308.
—. “ Intentionality and Physiological Processes: Aristotle’s Theory of Sense Perception.” In Essays on Aristotle’s De anima, edited by Martha Nussbaum and Amélie O. Rorty, 195–225. Oxford: Clarendon Press, 1995.
—. “Aristotle on Colour, Light and Imperceptibles.” Bulletin of the Institute of Classical Studies 47, no. 1 (2004): 129–140.
Spruit, Leen. Species Intelligibilis from Perception to Knowledge, Volume 1: Classical Roots and Medieval Discussions. Leiden: E. J. Brill, 1994.
Stothers, Richard. “Ancient Meteorological Optics.” The Classical Journal 105 (2009): 27–42.
Suárez, Francisco. Suarez commentaria una cum quaestionibus in libros Aristotelis De anima. Edited by Salvador Castellote. 2 vols. Madrid: Editorial Labor, 1575/1978.
Tachau, Katherine. Vision and Certitude in the Age of Ockham: Optics, Epistemology and the Foundation of Semantics 1250–1345. Boston: Brill Academic Publishing, 1988.
Taub, Liba. Ancient Meteorology. London: Routledge, 2003.
Van Hoorn, Willem. As Images Unwind: Ancient and Modern Theories of Visual Perception. Amsterdam: University Press of Amsterdam, 1972.
Waldman, Gary. Introduction to Light: The Physics of Light, Vision, and Color. New York: Prentice-Hall, 2002.
Ward, Jule. “Perception and Logos in De anima ii I 2.” Ancient Philosophy 8 (1988): 217–233.
Werrett, Simon. “Wonders Never Cease: Descartes’s Météores and the Rainbow Fountain.” The British Journal for the History of Science 34, no. 2 (2001): 129–147.
Westfall, Richard. “The Development of Newton’s Theory of Colour.” Isis 53, no. 3 (1962): 339–358.
Wilson, Malcolm. Structure and Method in Aristotle’s Meteorologica: A More Disorderly Nature. Cambridge: Cambridge University Press, 2013.
Witt, Charlotte. “Dialectic, Motion, and Perception: De Anima Book 1.” In Essays on Aristotle’s De anima, edited by Martha Nussbaum and Amélie O. Rorty, 27–56. Oxford: Clarendon Press, 1995.
Wolf-Devine, Celia. Descartes on Seeing: Epistemology and Visual Perception. Carbondale: Southern Illinois University Press, 1993.