“All men by nature desire to know.” This principle, with which Aristotle opened his Metaphysics, echoes throughout The Guide for the Perplexed. Knowledge, according to the Rambam, is more than the highest desire of human beings. It is also the true purpose of their life. However, not all items of knowledge are equal in this respect. Some are irrelevant to reaching my goals, such as knowing the exact height and weight of my desk. On the other hand, there is knowledge of a more difficult and complex kind, the attainment of which is critical to the meaning of my life. This knowledge is a higher rung on the metaphysical ladder of existence.
To grasp the significance of this idea in the Rambam’s thought, we need to first understand how medieval thinkers conceived of existence. At the center of the cosmos stood the Earth. However, its central place did not imply a preeminent importance. On the contrary, the Earth was made of the four physical elements that were at the very bottom of the metaphysical ladder of existence. Above the Earth were the spheres, which, according to medieval cosmology, were made of invisible matter. Resting on the spheres were the stars, which were believed to move in circular orbits.1 In the Middle Ages there were arguments about the number of the spheres, but there was widespread agreement about their essential nature. The spheres were thought to be living entities endowed with both intelligence and desire. Indeed, the movement of the spheres was believed to be caused by their yearning for metaphysical knowledge. Above the spheres were the separate intelligences. These were pure forms, devoid of material substance, to which the spheres were believed to aspire. Each sphere had a corresponding separate intelligence that it desired to know. Above it all was the unmoved mover, God, the summit of all existence. God was the cause of the motion of all the heavenly bodies, because all of them desired to know Him.
The medieval cosmos was alive. When man looked up at the night sky he saw beings that were suffused with intelligence and desire. To the modern mind, this picture of existence seems very strange. Modernity “killed” the cosmos and reconceived it as inanimate rather than alive. We no longer see the stars as intelligent beings, but as lumps of dumb matter moving through space. This is one reason for modern man’s sense of loneliness and alienation. The universe that was once full of life, intelligence and desire has fallen silent.
There is a further philosophical significance to the prevailing medieval model of existence. The force that was believed to cause the motion of the heavenly bodies was their thirst for knowledge. You might say that philosophy, literally the love of wisdom, is what moved the whole universe. So when people do philosophy, they are participating in this universal cosmic yearning for knowledge.
In sum, human intellectual progress was a journey from knowing objects that were on a lower metaphysical level to grasping things on ever more exalted metaphysical planes: from understanding the earthly world of the four elements to knowledge of the spheres, the separate intellects (non-physical entities whose existence was assumed in medieval metaphysics to explain the cosmic motion of the spheres), and ultimately knowledge of God.
Did Maimonides accept this classical picture of the cosmos? He sought to remove God from the confines of language and understanding. We have seen how the God beyond words and thought was inaccessible even to the greatest of the prophets, Moses. If we then take away God as a potential object of human understanding, we are left with the separate intelligences as the highest level of knowledge to which we may aspire.
Out of all the separate intelligences, the one that is most relevant to our discussion is the “active intellect,” the intelligence whose influence causes our physical world of the four elements to function. But can we ever know the “active intellect”? The Rambam’s view about this is unclear. He scattered oblique hints about the question throughout the Guide. His ambivalence provided fertile soil for many debates over the centuries about what he really thought.
One of the most convincing and carefully argued positions on this issue was developed by Shlomo Pines, a great twentieth-century Maimonides scholar. He based his view both on textual proofs from the Guide and also on comparisons with other philosophical texts in Maimonides’s oeuvre. Pines argued that, according to the Rambam, it is impossible to know the separate intellects. One of Pines’s most convincing proof texts is a passage in which Maimonides declared that he was uncertain as to whether the separate intellects exist. Aristotle inferred their existence from the movements of the spheres; their perfectly circular motion could only be understood as evidence that they were moved by the separate intellects. The Rambam viewed this inference as weak:
Know that the opinions held by Aristotle regarding the causes of the motions of the spheres from which opinions he deduced the existence of separate intellects—are simple assertions for which no demonstration has been made, yet they are, of all the opinions put forward on the subject, those that are exposed to the smallest number of doubts. (Guide, 2:3)
Not only were proofs for the existence of the separate intellects unconvincing, but the Rambam also cast doubt on whether we could know them even if they did exist.2
The limits of what reason could know contract still further. If the Rambam believed that God lay beyond the boundaries of human understanding and that the separate intellects were also outside those borders, then only the heavenly spheres remained as suitable supernal objects of human understanding. But Maimonides raised serious questions about even our ability to know these. In part 2, chapter 24 of the Guide, he elaborated on some of the most vexing problems in medieval cosmology and showed that the prevalent medieval vision of the universe, based on Aristotelian foundations and elaborated by Ptolemy, faced a serious crisis. There was a split between astronomy and physics. Astronomers described the movements of the heavenly bodies based on observation, but their findings could not be reconciled with the basic laws of physics:
See now how all these things are remote from natural speculation! All this will become clear to you if you consider the distances and dimensions, known to you, of every sphere and star, as well as the evaluation of all of them by means of half the diameter of the earth so that everything calculated according to one and the same proportion and the eccentricity of every sphere is not in relation to the sphere itself. (Guide, 2:24)3
Maimonides saw the conflict between astronomy and physics as evidence of essential shortcomings of the human mind. He believed that the stars and heavenly spheres were not accessible to our intellects and that most of Aristotle’s doctrines on this were therefore not relevant:
All that Aristotle states about that which is beneath the sphere of the moon is in accordance with reasoning. . . . However, regarding all that is in the heavens, man grasps nothing but a small measure of what is mathematical. (Guide, 2:24)
Aristotle’s teachings, which the Rambam termed “the pinnacle of human reasoning,”4 turn out to be unreliable regarding the sphere of existence that is beneath the moon.5 Reason must know its limits:
It [i.e., knowledge of the heavens] is a matter the knowledge of which cannot be reached by human intellects. And to fatigue the minds by notions that cannot be grasped by them and for the grasp of which they have no instrument, is a defect in one’s inborn disposition, or some sort of temptation. (Guide, 2:24)
This is a radical statement in the context of medieval philosophy—and also against the background of Maimonides’s thinking.6 The same Rambam who urged his readers to study the heavenly bodies, the stars, and the spheres as the fingerprints of God also wrote that the project of understanding the heavens could yield, at best, a very small degree of success. In his conclusion to this chapter, the Rambam sent a barbed message to anyone who thought that he had solved the crisis in medieval astronomy and physics:
That is the end of what I have to say about this question. It is possible that someone else may find a demonstration by means of which the true reality of what is obscure for me will become clear to him. The extreme predilection that I have for investigating the truth is evidenced by the fact that I have repeatedly reported my perplexity regarding these matters as well as by the fact that I have not heard, nor do I know a demonstration as to anything concerning them. (Guide, 2:24)
The author of the Guide admitted his perplexity about issues that lay at the heart of his book and of philosophy.7 The proofs for the existence of God relied on the movement of the spheres, and the proofs for the existence of the separate intellects were based on the circular motion of the heavenly bodies. Maimonides built an intellectual edifice upon the movement of the stars, and then, in a single chapter, he demolished the foundations of the whole project. The stars were placed outside the purview of reason. Out of all the cosmos, only the earthly world of the four elements remained accessible to our intellects.
To my mind, this is the central conclusion of the Guide: Maimonides, more than any other Jewish thinker, placed knowledge and understanding at the summit of our religious aspirations. Yet he was more skeptical than any other classical Jewish thinker about our capacity to acquire certain knowledge. How could someone who made reason so central to religious life also believe that the intellect is so limited?
We have seen a series of contradictions in the Guide about some of the biggest philosophical questions, such as whether the world was created and about the nature of God. Generations of scholars have puzzled over these riddles. To me, however, the greatest contradiction of the Guide concerns perplexity itself. Why did this book, which ultimately teaches that reliable answers to the great questions is unattainable, exhort readers to seek those answers? Why does the Guide take us on an ultimately futile journey? Before we grapple with this question, let us broaden it, for the crisis of astronomy and the perplexity of reason are symptoms of a broader collapse of authority, as we will see in the following chapter.