Endnotes
Prologue
* Tρελός means crazy.
I: That Dye of Dyes
1. Ball, Bright Earth, 198.
2. Throughout this book, we will describe the color of tekhelet as sky blue or azure. As will become clear, this is not a universally accepted position, and it certainly wasn’t the consensus opinion among scholars before the 1980s. Some scholars maintain that the hue tended more toward violet, a blue purple. The depth of the color is also debated, with some claiming it was a darker shade of blue. The reasoning that leads to the opinion that tekhelet is the color of the clear, cloudless, midday sky will appear later in the book.
3. The usual figure is something like 250,000 snails for an ounce of pure dye, based on the early twentieth-century research of chemists such as Paul Friedländer. Our numbers come from extensive experience with dyeing wool and probably fall closer to the numbers that ancient dyers would have realized.
4. Esther 8:15. All subsequent translations of the Bible come from The New JPS Translation According to the Traditional Hebrew Text, The Jewish Publication Society, Philadelphia, 1985.
5. Midrash Tanhuma, Shelach.
II: Ancient Times
6. The story of the loss and rediscovery of printing by movable type in some ways echoes that of shellfish dyeing—but in other ways opposes it. In the case of printing, the Minoan disc not withstanding, that technology played no role in ancient society, while today it’s hard to think of one more central to nearly every aspect of the modern world. Shellfish dyeing takes the opposite direction. It would be impossible to argue for the centrality of that art in today’s society, yet in ancient times it acted as a cornerstone in the economic, aesthetic, and political arenas.
7. Purple even crept into legends about the exploits of King Minos. According to one Greek myth, Minos once besieged the city of Megara, ruled by a king named Nisus who had a magical source of strength that made him invincible. One lock of his hair was colored purple. As long as this hair remained on his head, he and his kingdom could not be destroyed. But much like the biblical Samson, deceived by his lover Delilah, Nisus, too, was felled by a woman. In this story, it was his own daughter Scylla, who, either for love (of Minos) or for money, depending on the version of the legend, cut off her father’s purple lock and brought about the fall of his kingdom and the ruin of her city.
8. The Bible recounts that Cushan-Rishataim, ruler of Aram-Naharaim, sometimes identified as a Kassite king, conquered Israel just after the death of Joshua, Moses’s successor, and oppressed the Israelites for eight years (Judges 3:8).
9. Genesis 10:9.
10. I thank Professor Robert Stieglitz for directing me to his Biblical Archaeologist article in which he notes that small numbers of murex appear at the Early Minoan site of Myrtos (third millennium BCE), probably connected with diet rather than dye, although it is possible that Minoans made small quantities of the dye in the prepalatial period.
11. The linguistic evolution of the Mesopotamian terms for “blue wool” makes for a fascinating study in itself. Professor Wayne Horowitz of the Hebrew University, an expert in Mesopotamian history and language, explained it to me as follows: “In Ancient Mesopotamia, there was no word for the color blue either in Sumerian or Akkadian. Hence, the Sumerian za.gin = uqnû, the word for lapis lazuli, was adopted to mean lapis lazuli–colored, i.e. blue and its various shades and hues. This was apparently first applied to the sky, and when blue wool reached Mesopotamia also to this product: sig.za.gin.na = uqnâtu, for blue-colored wool. In what is most likely a secondary development, at least for Mesopotamia, the foreign words takiltu for blue and dark blue, and argammanu for purple, were introduced. These two terms were rendered into Sumerian as za.gin.gi6 = dark blue and za.gin.sa5 = red-blue, i.e. purple. The earliest actual mention of blue wool (sig.za.gin) in the Land of Israel is in ‘The Governor’s Letter’ from Aphek (around 1200 BCE).” See Horowitz, Cuneiform in Canaan.
12. Numbers 15:37–40.
13. Xun Zi, 8:23.
14. Milgrom, The Tassel and the Tallith, 2.
15. 1 Samuel 24:21.
16. Exodus 19:6.
17. Milgrom, The Tassel and the Tallith, 9.
18. Ezekiel 23:6.
19. Judges 5:30.
20. Deuteronomy 33:19.
21. Jeremiah 10:8–9.
22. Blum, Purpur Als Statussymbol in Der Griechischen Welt, 86.
23. Itamar Singer, “Purple-Dyers in Lazpa,” 22.
24. Astour, “The Origin of the Terms Canaan, Phoenician and Purple,”
25. Proverbs 31:24.
26. Zechariah 14:21.
27. See Elayi, The Phoenician Cities in the Persian Period, 14, and also Stern, Dor, Ruler of the Seas, 21.
III: Purple People
28. Ezekiel, in his prophetic warning of impending destruction, captures the reputation of the Phoenicians as wealthy traders throughout the ancient Near East, dealing with a remarkable variety of goods and customers:
Tarshish traded with you because of your wealth of all kinds of goods; they bartered silver, iron, tin, and lead for your wares. Javan, Tubal, and Meshech—they were your merchants; they trafficked with you in human beings and copper utensils. From Beth-togarmah they bartered horses, horsemen, and mules for your wares. The people of Dedan were your merchants; many coastlands traded under your rule and rendered you tribute in ivory tusks and ebony. Aram traded with you because of your wealth of merchandise, dealing with you in turquoise, purple stuff, embroidery, fine linen, coral, and agate (27:12–16).
The long list continues: wheat, honey, oil, balm, wine, white wool, polished iron, cassia, calamus, saddlecloths, lambs, rams, goats, spices, precious stones, gold, choice fabrics, embroidered cloaks of blue, and many-colored carpets.
29. This story appears on a wonderful coin minted in Tyre between the reigns of Elagabalus (218–222 CE) and Gallienus (253–268 CE). On the bottom of the coin a dog and a murex are portrayed, recounting the story of Melkarth and the discovery of the purple shellfish dye. On the top of the coin are the two Ambrosial rocks that flank an olive tree. The legend told by Nonnus from Panopolis in his Dionysiaca has these two rocks floating on the sea, and on one of the rocks an eagle perched upon a burning olive tree and a snake curled around it. Melkarth ordered his people to build boats to follow the rocks, and Tyre was founded where they came to rest. See Bijovsky, “The Ambrosial Rocks and the Sacred Precinct of Melqart in Tyre.” I thank Donald Tzvi Ariel, head of the Coin Department for the Israel Antiquities Authority, for bringing this article to my attention.
Another depiction of this scene appears in The Discovery of the Secret of Purple by Peter Paul Rubens. The snail in that work is clearly a figment of the painter’s imagination—certainly not a murex.
30. Diodorus Siculus, Bibliotheca historica, bk. 20, lines 6–7.
31. “Now I am sending you a skillful and intelligent man, my master Huram, the son of a Danite woman, his father a Tyrian. He is skilled at working in gold, silver, bronze, iron, precious stones, and wood; in purple, blue, and crimson yarn and in fine linen.” (2 Chronicles 2:12–13).
32. Ezekiel 27:7.
33. Ezekiel 28:17.
34. 2 Chronicles 36:18.
35. Rogers, Cuneiform Parallels to the Old Testament, 313.
36. In Plutarch’s Parallel Lives, “Solon” bk. 5, sec. 2.
37. Pliny the Elder, The Natural History, bk. 7, chap. 57.
38. Homer, Iliad, bk. 13, lines 1–7.
39. Jeremiah 4:13.
40. Herodotus, Histories, bk. 4, lines 73–75.
41. Polosmak, Textiles from the “Frozen” Tombs in Gorny Altai 400–500 BC—An Integrate Study, 222–23.
IV: Exploring Dora
42. De Bourrienne and Phipps, Memoirs of Napoleon Bonaparte, vol. 1, chap. 19.
43. Geologists debate the received wisdom that kurkar marks ancient coastlines. Optically stimulated luminescence, a method that measures the last time a substance was exposed to sunlight, provides information that indicates great variability in the formation dates of each ridge and no great differences between ridges.
44. The Greeks extended their influence over Dor, though some eighteenth- and nineteenth-century scholars held that the reverse also happened. They claim that the founders of Paestum in Italy came from Dor, and the temples that were built there may have given the Doric name to one of the three orders of Greek architecture. Noted professor of architecture Richard Brown quotes this view in his Domestic Architecture, 62. The suggestion is older than that, as Brown mentions in a footnote, originally proposed by A. Mazzocchi in Commentarii in regii Herculanensis Musei aeneas tabulas Heracleenses, vols. 1 and 2 (Naples, 1754–55). We must take Mazzocchi’s theory, however, with a grain of salt. Though one of the premier classicists and orientalists of the eighteenth century (one contemporary called him “the most learned Grecian of our time”), Mazzocchi was also a very proud Italian who sought to prove that the greatness of the Greeks came from their contacts with Italy, and the ancient Italians, in turn, directly descended from biblical migrations. There is no conclusive connection between Tel Dor and the Dorian Greeks or the Doric architectural order. S. R. Martin recently proposed a similar, though opposite, theory. The Hellenic inhabitants of Dor cleverly punned on the similarity of the Semitic “Dor” to the Greek Dorians, to manufacture a Greek ancestry.
45. Conversation with the author.
46. Ilan Sharon also questions this hypothesis. In correspondence he wrote: “What bothers me is the lack of evidence for heating/fermenting installations in that particular courtyard. I cannot escape the conclusion that this installation was used only for the first stage of the process (breaking the shells and treating the raw mollusk with quicklime)—and that further processing was done somewhere else.”
47. De Bourrienne and Phipps, Memoirs of Napoleon Bonaparte, vol. 1, chap. 19.
48. Cvikel et al., “Napoleon Bonaparte’s Adventure in Tantura Lagoon,” 199.
49. De Bourrienne and Phipps, Memoirs of Napoleon Bonaparte, vol. 1, chap. 19.
* The pits on these islands can be deceptively deep. On one excursion, my then-four-year-old son stepped into what he thought was a shallow hole and had to be scooped up before drowning.
V: Only God Can Tell
50. Babylonian Talmud, Baba Metziah 61b.
51. Deuteronomy 22:11.
52. Midrash Sifre, Shelach.
53. Babylonian Talmud, Menachot 42b.
54. Ibid.
55. Ibid.
56. See Rashi’s commentary on Exodus 25:4 as compared to his commentary on Numbers 15:41.
57. There are some who disagree and actually arrive at the exact opposite conclusion. They maintain that tekhelet could not be the exact molecular equivalent of kala ilan, since the Talmud does propose that tests could distinguish between them. In my opinion, this argument is not credible. On the basis of current understanding of the dye chemistry and the standard interpretation of the Talmudic tests, those procedures would not cause any change in cloth dyed with plant based indigo, kala ilan, which was meant to fade under their influence. If one wants to uphold the chemical efficacy of the tests, one would have to posit that there are some yet-to-be-understood reactions that involve, perhaps, the methods by which the ancients dyed. If this is true, then one can take that reasoning further and apply it to murex dyeing as well. After all, there are significant amounts of many other substances along with indigo in murex-derived dye. Even if those additions are too small to be detected by the eye and change the perceived hue, they may play some little understood chemical role that is picked up via the Talmudic tests.
VI: The Missing Shade of Blue
58. Yadin, The Finds from the Bar-Kokhba Period in the Caves of the Letters, 182–87.
59. Arrian of Nicomedia, Anabasis, bk. 6, chap. 29.
60. Pliny the Elder, Natural History, bk. 9, chap. 36.
61. In later centuries, purple—though not from shellfish—was the distinguishing and exclusive color of European royalty as well, often legally regulated. Elizabethan sumptuary laws, for instance, restricted the use of purple to the royal family and higher nobility. The purple of royalty, however, also had less glamorous associations. Mary Queen of Scots and England’s King George III are said to have suffered from a rare genetic abnormality known as porphyria. It gets its name from the purple color of the patient’s stool and urine and is caused by a disruption in the production of heme, a component needed for healthy blood cells. In some cases the nervous system is affected, leading to seizures, hallucinations, and other mental disorders. Many suggest that the dementia suffered by the king of England and referred to as the “madness of King George” was due to this disease rather than to grief over losing the American colonies.
In the realm of legend and folklore, there have been suggestions that the belief in vampires derives from cases of porphyria. In 1985, in a talk before the American Association for the Advancement of Science, biochemist David Dolphin offered a spine-chilling suggestion. He proposed that “blood-drinking vampires were in fact victims of porphyria trying to alleviate the symptoms of their dreadful disease.”
Afflicted individuals supplied their bodies with the heme molecules they lacked by sucking and ingesting human blood. The biochemist found support in the fact that porphyria can lead to photosensitivity, where exposure of the skin to light can cause great pain, which explains the vampire’s aversion to sun. Porphyria can also lead to a tightening of the gums, tending to make the teeth protrude, like fangs. And what is known to exacerbate the symptoms? Garlic, of course!
62. Reinhold, History of Purple as a Status Symbol in Antiquity, 71.
63. Dio Cassius, Roman History, bk. 49.
64. Seutonius, De Vita Caesarum, Nero, 32.
65. Herzog and Spanier, The Royal Purple, 110.
66. Babylonian Talmud, Sanhedrin 12a.
67. Eusebius Pamphilius, Church History, Life of Constantine, Oration in Praise of Constantine, Ch. XXXIII:3.
68. Pharr, Theodosian Code and Novels, 288.
69. Babylonian Talmud, Menachot 43b.
70. Babylonian Talmud, Menachot 42b.
71. Midrash Tanhuma, Shelach.
72. In a much later source, a passage appears that some use to claim that Jewish blue and purple dyeing continued long after this, namely the twelfth-century travel log of the intrepid Benjamin of Tudela. There is much confusion regarding what exactly Benjamin found when he visited Tyre. For example, the article on “Dye and Dyeing” in the Jewish Encyclopedia, first published in 1906, states: “In the twelfth century the Jews of Tyre were still purple dyers and manufacturers of glass (see Benjamin of Tudela, Travels, ed. Asher, p. 30b).” Rabbi Herzog also makes this assertion in The Royal Purple (p. 112). Asher indeed translates the log of Benjamin (The Itinerary of Rabbi Benjamin of Tudela, vol. 1 [New York: Hakesheth, 1840], 63) as follows: “The Jews of Tsour [Tyre] are shipowners and manufacturers of the far-renowned tyrian glass, the purple dye is also found in this vicinity.”
But Adler’s translation (1907) has “The Jews own sea-going vessels, and there are glass makers amongst them who make that fine Tyrian glass-ware which is prized in all countries. In the vicinity is found sugar of a high-class, for men plant it here, and people come from all lands to buy it.” We have sugar now instead of purple dye. The Hebrew original isn’t clear either, with various manuscripts giving asukar, hasikar, or hatzukru. Asher’s Hebrew manuscript reads hasikar. Both he and Rabbi Herzog translate that word as coming from sikra, meaning red, and render that as purple, perhaps influenced by the Tyrian connection. But looking at the other versions and manuscripts convinces me that Adler’s translation is correct, and in the twelfth century the Jews of Tyre dealt in sugar, not in snails.
* Hyacinth is the term the ancients used to describe what we call blue, and the ancient Greek translation of the Hebrew Bible, known as the Septuagint, translates the word tekhelet as “iakintos”—hyacinth.
VII: Mood Indigo
73. Dendel, You Cannot Unsneeze a Sneeze and Other Tales from Liberia.
74. The story also turns out to reveal a very real, though extremely rare, physiological phenomenon: Blue Diaper Syndrome. The disorder involves the metabolism of tryptophan, an amino acid essential for the human diet. According to an article in the American Journal of Medicine, “Bacterial degradation of the tryptophan leads to excessive indole production and thus to indicanuria which, on oxidation to indigo blue, causes a peculiar bluish discoloration of the diaper.” Indicanuria is the excretion through urine of indican, a precursor of indigo dye that turns blue on exposure to oxygen in the air (Drummond, “The Blue Diaper Syndrome”).
75. Julius Caesar, The Gallic Wars, bk. 5, chap. 14.
76. E-mail correspondence with the author.
77. Balfour-Paul, Indigo, 127.
78. Ibid., 100–102.
79. Sandberg, Indigo Textiles, 19. Other descriptions of this process are less cheerful. Balfour-Paul, for example, writes: “Groups of near-naked men and women had to walk up and down waist deep in the slimy liquid for several hours, beating it with implements such as wooden paddles, or even with their bare hands…. [The tanks were labeled] ‘devil’s tank’, as the terrible fumes … ‘killed many workers.’ Local populations were understandably reluctant to undertake a job said to cause, if not death itself, at least cancer, impotence, headaches, and temporary lameness” (Balfour-Paul, Indigo, 110–11).
80. Bemiss, The Dyer’s Companion.
81. Edmonds, The History of Woad and the Medieval Woad Vat, 26.
VIII: The Quest for the Holy Snail
82. In the narrative that follows I have drawn on the works regarding the history and teachings of Ishbitz/Radzyn by Shlomo Zalman Shragai, an Israeli politician, the first democratically elected mayor of Jerusalem (1950–52), and a devout Hasid of Radzyn.
83 Morris Faierstein in All Is in the Hands of Heaven, on Mordechai Yosef Leiner’s teachings, includes an appendix entitled “The Friday Night Incident in Kotsk: History of a Legend.” The chapter begins: “The antinomian legend of the ‘Friday night incident’ in Kotsk is one of the best-known Hasidic tales. Its truth or falsehood has been discussed for the last sixty years.” Faierstein attempts to trace the historical development of the story and to assess whether it was accurate and even plausible.
In the version that I present, I have taken parts of the story from Martin Buber’s account in Der Grosse Maggid und Seine Nachfolge as well as from the memoirs of a member of the Leiner family, Dor Yesharim, originally published in 1925 and reprinted in S. Z. Shragai’s Bmaayanei Chasidut Ishbitz-Radzyn.
Some scholars and many Hasidim argue that the incident never took place. If it did happen, Leiner is said to have played a central part, though the exact nature of his role is debated. What is certainly true is that Leiner broke with Menachem Mendel around the time that the latter went into seclusion, and that a feud ensued between subsequent generations of Kotsker and Radzyn Hasidim.
84. Leiner, Ptil Tekhelet, 8.
85. Babylonian Talmud, Menachot 44a.
86. Shir HaShirim Rabbah, 4:23.
87. Leiner, Sefunei Temunei Chol, 33, based on the Mishna Kelim, 12:1.
88. Maimonides, Mishneh Torah, Hilchot Tzitzit, 2:1.
89. Babylonian Talmud, Shabbat 75a.
90. Shragai, Bi-netive Hasidut Izbitza-Radzin, vol. 2, 194, 198.
IX: True Blue
91. One of the other rabbis from whom Herzog received ordination was the world-renowned Rabbi Jacob Vilkowsky, whom he saw as his ultimate mentor and for whom he named his second son, Jacob.
92. Herzog’s relationship with Sinn Féin rebels and the influence that his friendship with de Valera had on his intellectual outlook offers a fascinating study in itself. Both men dealt with the complex interplay of state and religion, and how to ensure the rights of the minority while allowing for a country with a specific national religious character. See Matveev, “The Rebbe of Sinn Féin.”
93. Rabbi Herzog’s grandson and namesake, Yitzchak Herzog (nicknamed Bougie in Israel), the Israeli minister of Welfare and Social Services, represents the Labor party in the Knesset and has earned a reputation for being an advocate for the rights of the disadvantaged and a defender of the working class. “Though my grandfather died a year before I was born,” he told me over a cup of green tea in a Tel Aviv cafe, “his values and ideals permeated our house and made a deep impression on me. His attitudes towards religion and state were greatly influenced by his years in Dublin watching the nascent country fight for and gain its independence. He was a fervent Zionist who believed in harmonizing Judaism and democracy, and together with my grandmother Sarah built a home based on charity and kindness. These values were absorbed by my father, Chaim, who served as a general in the Israeli army, ambassador to the United Nations, and later as Israel’s sixth president. His feelings of compassion towards others, in my opinion, were amplified during his years as a British officer in World War II, where he saw the horrors of war firsthand. I grew up in a family of people who care for people.”
94. Shaul Meislish, “Toldot Harav Herzog,” in Maśu’ah Le-Yitshak, ed. Eliash, Warhaftig, and Dosberg, 19.
95. A number of versions of this story exist. Rabbi Herzog’s son Jacob, in an interview to the radio station Galei Zahal in November 1969, asserted that it was indeed President Roosevelt who asked his father not to return to Israel. Others maintained that it was Lord Halifax who sent a messenger to Rabbi Herzog explaining that, in light of Rommel’s advance, the British government was considering evacuating their citizens from the Middle East. Halifax counseled that Rabbi Herzog, as a British citizen, should stay in America. Still another version places the conversation between Rabbi Herzog and the mayor of New York City, Fiorello La Guardia. For a full discussion see the article by Ari Shvat, “Rabbi Herzog’s Certainty That There Won’t Occur a Third Destruction,” in Maśu’ah Le-Yitshak, Part II, ed. Eliash, Warhaftig, and Dosberg.
96. McCullough, Truman, 620.
97. Herzog and Spanier, The Royal Purple, 116.
98. Ibid.
99. Ibid., 131 n. 410.
100. Professor Mary Orna kindly pointed out that Prussian blue served as the key clue in solving another case of ancient authenticity. “Archaic Mark” as it became known, or MS 2427 in the scholarly jargon, is a beautifully illuminated miniature manuscript of the Gospel of Mark, presumed to date from the thirteenth century. That’s certainly what the University of Chicago thought when it acquired the codex in 1937. But since that time, scholars have argued about it. Some believe it to belong to Category I codices (that is, Alexandrian-type texts usually from the fourth century or earlier). Others had doubts. In 1988 Professor Orna tested the pigment contained in one of the illustrations and found it to include none other than Prussian blue, proving that the codex couldn’t be any older than 1704, when Diesbach discovered it. Subsequent textual investigation by Stephen Carlson and more detailed chemical analysis in 2006 by Mitchell, Barabe, and Quandt confirmed it to be a nineteenth- or even early twentieth-century forgery.
101. Bartoll, “The Early Use of Prussian Blue in Paintings.”
102. See Yaakov Leiner, “Mifal Tzviat HaTekhelet BMidinat Yisrael,” in HaTekhelet, Burshtein, 59–63. See also the chapter “Hidush HaTekhelet B’Medinat Yisrael,” 197–204.
103. As Herzog put it, “Science knows nothing of such a septuagenarian ‘appearance’ of any of the denizens of the sea” (Herzog and Spanier, The Royal Purple, 69).
104. Herzog, “Hatekhelet B’Yisrael” 11:2, in HaTekhelet, Burshtein, 422.
105. Babylonian Talmud, Shabbat 26a.
106. Shir HaShirim Rabbah, 4:23.
107. Edelstein himself published another important manuscript—namely Rabbi Herzog’s dissertation. Through Edelstein’s funding, librarian Moshe Ron took on the project of transcribing, translating, and editing the handwritten work. It appeared in 1987 in book form, edited by Ehud Spanier, together with many articles describing the current state of tekhelet research.
108. This is one version of the apocryphal stories of the serendipity that led to Elsner’s discovery of the photochemical processes that debrominate snail dye. It may not have been completely accidental, though, and Elsner may have been looking for such effects. As an experienced indigo dyer, he knew that dyeing in direct sunlight could change the color somewhat. He also may have seen the paper by Driessen, who first suggested this phenomenon (Driessen, “Über Eine Charakterische Reaktion Des Antiken Purpurs Auf Der Faser”).
109. Some chemists and archaeologists believe that ancient dyers wouldn’t have produced sky blue and wouldn’t have figured out how to obtain that color. They argue that, since the fermentation process, which is necessary to make the murex extract suitable for dyeing, is more efficient in oxygen-poor conditions, the dye vat had to be kept closed and away from direct sunlight. Dyers, therefore, wouldn’t have observed the effects of photo-debromination turning purple to blue, accomplished as it is in the open air and bright sunlight.
I find this position highly implausible since we have discovered many ways to achieve azure blue from the murex dye, whether through sunlight or steam, and I am quite sure that ancient dyers practicing their craft over thousands of years would have noticed this phenomenon. To be fair, though, modern researchers didn’t know about the photo-debromination until Elsner’s discovery.
X: The Selfish Shellfish
110. Dr. Harry G. Lee kindly pointed out the passage from Linnaeus and its interpretation. In an e-mail to me, Dr. Lee wrote:
The species epithet was employed as an appositional noun. We know this because Linnaeus consistently initiated species epithets with upper case if nominative and lower case if adjectival. Trunculus is the diminutive of truncus, and both are used as nouns or adjectives in Latin. In the context of Linnaeus’s concept of Murex, one meaning of trunculus: “little cut-off,” seems apt. As I look through the taxa the master considered congeners, many of them have much longer siphonal canals. He wrote “M[urex] testa ovata nodosa anterius [sic] spinis, cauda breviora truncata perforata” [my boldface] (Linnaeus 1758:747). I think he was trying to capture the chopped-off canal (cauda).
Though Dr. Lee is probably correct in attributing the “truncation” that Linnaeus mentions to the canal (cauda means tail), I chose to ascribe that appellation to the spines. The correspondence to the colloquial Hebrew was too good to pass over. In addition, Linnaeus does speak of spinis, which could mean spine or prickle, so I felt license was justified.
111. The murex also secrete choline esters, which are muscle relaxants. Injecting these into their prey helps the murex subdue their victims for long periods. The esters also help relax the adductor muscle in bivalves for the murex to gain access to the meat without having to bore through the shell. Dr. Benkendorff observed that these chemicals make abalone loosen their grip on the substrate to which they had attached, so the snails can flip them over and feast en masse.
112. Indole forms from a six-sided benzene ring attached to a five-membered pyrrole ring. Used since the fifteenth century, benzene was originally known as “frankincense of Java.” The chemical formula for benzene, namely its six carbon atoms, was understood early on, but the actual structure remained a puzzle for many years. German chemist Friedrich Kekulé first proposed the ring formation in 1865 after waking from a dream in which he saw a snake eating its own tail.
113. The murex family, through multiple precursor pathways, actually produces a number of dyes that fall into three general categories based on the fundamental molecules: indigo, indirubin, and isatin. The first two have the same molecular formula; that is, they have the same types and amounts of each atom, but they differ structurally. These types of molecules are called isomers. Where indigo is aligned linearly, indirubin is L shaped. The third, isatin, is essentially an oxygenated version of indole or half an indigo molecule. In each of these groups, additional dye molecules form when bromine replaces one or two of the hydrogen atoms. Since indirubin and isatin are not symmetrical, the position of the bromine atom makes a difference. The following table illustrates the ten dye molecules that the murex can produce.
This information comes from data in the articles by Koren cited in the bibliography and is based mostly on the table in his article from 2006, “HPLC-PDA analysis of brominated indirubinoid, indigoid, and isatinoid dyes.”
114. Aristotle, The History of Animals, bk. 5, part 15 (translated by D’Arcy Wentworth Thompson).
115. Babylonian Talmud, Shabbat 75a.
116. Dr. Kirsten Benkendorff, of Southern Cross University, confirms that the synthesis of the dye precursors—including bromoperoxidase activity—does indeed increase before and during mating.
117. Earlier research into the correlation of dye production with snail sex claimed the opposite. See, for example, Elsner, “Solution of the Enigmas of Dyeing Tyrian Purple and the Biblical Tekhelet.” Benkendorff’s experiments appear more conclusive, though more research is necessary to complete our understanding.
118. Professor Ehud Spanier from Haifa University suggested a different use that the murex might make of tyriverdin, namely as a pheromone. He proposed that the molecule could signal a chemical call to other murex to join together for mating and egg laying. Murex do tend to gather and lay their eggs en masse. This may also explain why males and not only egg-laying females produce the substance. Again, more research is necessary to confirm this hypothesis.
119. Professor Skaltsounis at the University of Athens School of Pharmacy is carrying out this work.
120. See Babylonian Talmud, Bava Metzia, 61b.
XI: Dyed in the Wool
121. Jerusalem Talmud, Shabbat, chap. 1, Halacha 3. See the commentary of the Pnei Meir.
122. Acts 16:11–15.
123. Faber, Dyeing and Tanning in Classical Antiquity, 285.
124. I thank Georg Stark, master blue dyer, for providing this information. By the way, here’s a tip for gamers of the popular online RuneScape fantasy world: Aggie the witch can provide you with blue dye.
125. Pliny the Elder, Natural History, bk. 9, chap. 62.
126. Babylonian Talmud, Menachot 42b.
127. Elsner, “The Past, Present and Future of Tekhelet,” 175.
128. Edmonds published two books: Chaucer in Modern English Prose: The Canterbury Tales; and Chaucer’s Other Works: In Modern English Prose.
XII: Seeing Blue
129. This is not strictly true. There are five ways to turn white light into blue. There are other ways to make blue in the universe. Some have to do with radiation—that is, generating light—which can be preferentially blue. A gas flame is blue. The water surrounding nuclear reactors gives off a beautiful blue in a process known as Cherenkov radiation. Kurt Nassau’s The Physics and Chemistry of Color details all fifteen ways that color can be generated.
130. When the revolution of modern physics came about, British poet J. C. Collins extended the poem with:
It did not last: the devil, shouting “Ho.
Let Einstein be,” restored the status quo.
131. The cones, however, aren’t evenly distributed; about 64 percent are red or L cones, 32 percent are green or M, and only 2 percent are blue or S. Though these are so much scarcer, they are the most acutely sensitive to light. Humans can detect blue as effectively as red, but the lower density of the S cones means that the spatial resolution of blue is less than that of red.
Another, perhaps related, observation (for which I thank Professor Ari Zivotofsky) has to do with the plane of focus of the eye. Since, as Newton pointed out in his experiments on “refrangibility,” different colors bend to different degrees through prisms and lenses, the eye focuses red at a slightly different plane than blue. The retina is placed for optimal focus of L and M cones, namely red and green, so all the blue that we humans see is slightly blurred. The blue that we do see, blurred or not, comes primarily from the indiscriminate sky and ocean, where sharp lines don’t play a prominent role. It appears that, in the development of the human visual system, blue objects, so rare in nature, didn’t present a significant requirement that needed accommodating.
132. Humans who have one or two types of cones are said to be color-blind. Women have a higher sensitivity to color, for which there may be a physiological basis. As a recessive gene on the X chromosome, color blindness affects mostly men; 8 percent of the male population has some form of color blindness, whereas in women the frequency measures ten times less. In some rare cases, women develop a fourth cone (sensitive in the yellow region) that gives these lucky individuals even greater color perception. Genderrelated genetic attributes may or may not have to do with women showing a greater faculty for color discrimination than men and girls learning to identify different colors earlier than boys.
There is an extremely rare type of color blindness, known as achromatopsia, where the person has no cones, only rods, and can’t see any color at all. This condition is described in Oliver Sack’s wonderful book, The Island of the Colorblind.
133. The interaction of light and matter on the most fundamental level occurs when a photon strikes an atom or molecule. In order for the photon to be absorbed, thereby transferring its energy to the atom or molecule, those particles have to be able to “do something” with the photon’s energy. Molecules can absorb photons and start to rotate and vibrate, but the wavelengths that excite those modes are much longer than visible light, so all the energy transitions that take place in that range play no part in our perception of color.
According to quantum mechanics, molecules and atoms never stop moving—but they’re not free to move at random; they must occupy specific and discrete energy states. In their ground state, they may rotate at specific speeds and specific energies, but when hit by the right photon, they can jump from a lower to a higher level. That happens only when the energy jump from one state to another precisely matches the energy of an incoming photon, as determined by the photon’s wavelength. In that case, the molecule can absorb the photon and change its rotational speed. When it falls back to a lower energy level, the molecule slows down, moving from the higher energy state to a lower state in a single jump, emitting a photon with exactly the wavelength that corresponds to the drop in energy. This is the process that takes place, for example, in a microwave oven, in which the radiation corresponds to the wavelength that induces water molecules to rotate. The water in your food absorbs those photons and spins, bumping into the other food molecules along the way, thereby heating them up. The wavelengths that induce rotational states measure thousands of times longer than visible light (microwave ovens emitting a wavelength of about 12 cm), and so our eyes can’t see them.
At shorter wavelengths and higher energies, the absorption of photons by molecules causes the atoms in the molecule to vibrate. Again, quantum mechanics constrains this movement to discrete energy states, and moving from one vibrational mode to another involves a jump in energy defined by the precise wavelength of the photon required to excite that mode. The wavelengths involved in vibrational transitions, though shorter than those needed to excite rotational states, are still longer than visible light and fall within the infrared region.
134. To explain this a little more, let’s use, as an analogy for a molecule, atomic balls held together by springs. Changing two factors can speed up the vibration: lighter balls or tighter springs. Bowling balls on a long loose spring will vibrate more slowly than Ping-Pong balls on a short tight spring. For vibrational energy to move up toward the visible, you need the lightest ball, hydrogen. The water molecule resembles Mickey Mouse, with an oxygen head and two hydrogen ears. A curious characteristic of the water molecule—discussed in Michael Brooks’s 2008 book, 13 Things That Don’t Make Sense—is that even in its natural stable state it can form chains and structures, with tens or even hundreds of water molecules coming together. These clusters tend to “tighten the spring” and drive the vibrational energy a bit closer to visible—but still not close enough.
To get there requires harmonic overtones of the vibration, a property familiar to musicians. Pluck a taut string, and you hear a tone that comes mostly from its vibration at a fundamental frequency, with an added richness from higher harmonics (twice the fundamental frequency, thrice, etc.). Suppressing the fundamental frequency allows those higher harmonics themselves to be heard clearly; guitarists do this by lightly touching a string at the twelfth fret, which shortens the string by a half, as in the classic introduction to the song “Roundabout” by Yes.
Putting all these processes together, the vibrational energy of the higher harmonics of a water cluster just barely reaches the wavelengths of visible light. As a result, water slightly absorbs red light just enough to make the ocean look blue.
135. Occasionally, however, along with absorption in the blue region, a molecule can have a rogue electron transition that also absorbs red.
The chlorophyll in plants, for instance, absorbs both blue and red, and this absorption results in the lush green of grass and leaves.
136. As reported in Wouters and Verhecken, “High-Performance Liquid Chromatography of Blue and Purple Indigoid Natural Dyes.” Though it must be noted that other experiments give a slightly different absorption peak that seems to depend on the solvent used.
Six hundred thirteen also happens to be an important number in Jewish lore, representing precisely the number of commandments that tradition claims the Bible contains. Furthermore, letters of the Hebrew alphabet—like those of Arabic, ancient Greek, and Latin—were also used as numbers. A subset of what we call numerology, the practice of gematria, or isopsephy, as the Greeks called it, involves calculating the numerical value of words. Words with the same numerical value share an affinity with each other, thought to convey a hidden idea or some significant relationship that exists between the word and its number value. According to some scholars, the Hebrew word tzitzit—the fringes on the corners of a garment—yields a value of 613. Wearing the tzitzit therefore numerologically reminds all who wear them to observe all 613 commandments.
That the tekhelet molecule, indigo, gets its deep sky-blue color from a strong absorption peak centered exactly at 613 nanometers makes for a remarkable coincidence linking ancient tradition and modern chemistry.
137. Dye chemists assert that the part of the indigo molecule responsible for its color lies in the center and refer to it as the H-chromophore, due to its H-like shape. Proof that symmetry plays an important role in bringing the absorption spectrum of indigo to such uniquely long wavelengths comes from examining the property of its isomer, indirubin. That molecule has an identical atomic formula and consists of the same atoms, but its geometric structure is L shaped. The letter H has more axes of symmetry than the letter L, which must rotate a full 360 degrees to return to its original position. Changes in the electron configurations of indirubin require greater energy so that its absorption of light, more typical than that of indigo, falls in the higher energy blue end of the spectrum, giving it a more earthy, less heavenly red tone.
* It sounds more painful and less interesting than it will be.
XIII: Feeling Blue
138. Esther 1:6.
139. Finlay, “Weaving the Rainbow,” 401.
140. Goethe, Goethe’s Theory of Colours, 329.
141. Bush and Shih, Early Chinese Texts on Painting, quoted in Finlay, “Weaving the Rainbow,” 410.
142. The blue and white of the Israeli flag were inspired by the tekhelet and white tzitzit of the Jewish prayer shawl. The powerful symbolism that Rabbi Soloveitchik describes, according to which the tekhelet reminds one of the unpredictable course that history often takes, is especially poignant with respect to Jewish history, and the blue in the flag evokes the mystery of the events and processes that ultimately led to the reestablishment of a Jewish homeland after 2000 years of exile. For a thoughtful interpretation of the relationship between tekhelet and the Israeli flag, see the play, “The Flag that Came Out of the Blue,” in Old Wine, New Flasks, by Roald Hoffmann and Shira Leibowitz Schmidt.
143. Blue light can also treat skin conditions such as acne. Recent studies, however, advise extreme caution regarding overexposure to intense blue light, which seems to induce photooxidative damage that leads to age-related macular degeneration.
144. Klein, The Chelsea Hotel Manifesto, 1961. Quoted from the Yves Klein Archives website.
145. Cotel never lacked inspiration for his musical pieces. In his obituary, the New York Times (nytimes.com/2008/11/03/arts/music/03cotel.html) recounted that:
In 1996, while he was at his piano playing Bach’s Well-Tempered Clavier, his 3-year-old cat, Ketzel, pounced on the keyboard. The professor grabbed a pencil and inscribed a descending paw pattern from treble to bass. A year later, he entered the score—if one can call it that—in the Paris New Music Review’s One-Minute Competition, open to pieces of no more than 60 seconds. The judges gave Ketzel an honorable mention.
146. From a personal correspondence.
147. Galileo, Il Saggitore, trans. A. C. Danto in Columbia College, Introduction to Contemporary Civilization in the West, 789.
148. Hyman, The Objective Eye, 14.
149. Hoeppe, Why the Sky Is Blue, 13–14.
150. Nabokov, Laughter in the Dark, 291. It is not, of course, Nabokov himself who speaks the words, but rather his character.
XIV: Tangled Up in Blue
151. The notion that artistic or aesthetic motivations enter into what many view as a cold, rational, legalistic realm of Jewish law may seem strange, but that appears to be the case with regards to tekhelet. For example, Abraham ben David, a leading twelfth-century legal scholar from Posquières in France, chose a specific method of tying that “is arranged in a very pleasing arrangement.” Note also the instructions of Rav in the Talmud concerning the most attractive ratio for the tzitzit. See Navon, “Rav’s Beautiful Ratio.”
152. Two options for a sustained supply of murex dye remain to be investigated. The first, growing or farming the snails, our group has looked into on a very cursory level, having commissioned some research at the University of Miami into the conditions and parameters required. Another alternative is to develop techniques for eco-friendly extraction of the dye—that is, “milking” the snails—on an industrial scale. This would be the ideal method of choice for many reasons, and it is my personal hope that such a process comes to pass.
153. I heard this philosophical insight from the Radzyner Hasid who is currently responsible for dyeing the cuttlefish-based tekhelet. He attributed this idea to Gershon Henokh himself. How fitting and appropriate a thought for the Radzyner rebbe, who embodied the idea of risking everything in order to achieve one’s mission, and who stands as a role model to all in this respect.
154. Pliny the Elder, Natural History, bk. 9, chap. 37.