Guide, was reading the two authors together, or would simply turn to The Wars of the Lord at appropriate points (perhaps guided by a teacher, or by another commentary).
Duran refers to Gersonides on key questions of epistemology, divine knowledge of particulars, and divine providence.42 On astronomical issues, there is no clear evidence that Duran had yet read and absorbed the highly technical astronomical sections of The Wars of the Lord. Still Duran does cite Gersonides twice in his comments on Guide II.24, where Maimonides discusses the problem of contradictions between Aristotelian physics and Ptolemaic mathematical astronomy (to which we will return at greater length in Chapter 5). Maimonides asserts that a “true perplexity” is the fact that the mathematical models of Ptolemy, which employ epicycles and eccentric orbs, come into conflict with the physics of Aristotle, which states that celestial matter is constrained to move in perfect circles of constant motion about a fixed point, namely, the center of the earth.43 This particular issue is picked up on by Duran:
Maimonides: If epicycles exist, theirs would be a circular motion that would not revolve about an immobile thing.
Duran: He means that it has already been explained in natural science that all that moves must move with respect to an immobile thing, and this epicycle, if we posit that it exists, would move with respect to the sphere which is something not immobile. And the solution to this doubt is not difficult, for the premise made there, that everything that moves does so with respect to an immobile thing does not mean that that which moves does so with respect to a body that is primarily immobile, but it means to explain that it is not possible for there not to be an immobile body with respect to which it revolves, [even if] it moves with respect to a thousand moving bodies one after the other, so that all of them require that it be immobile. And the proof of this is that a man moves with respect to a boat and it moves, indeed, because the waters are immobile. It has already been verified that the man moves upon an immobile thing and that is the water. And thus explained ha-rav R. Levi of blessed memory: even though the epicycle moves with respect to the sphere, and it moves, since the larger [sphere] moves around something fixed [namely, the center of the earth], therefore the epicycle moves with respect to an immobile thing.44
Duran here seems to be defending, to some extent, the practice of mathematical astronomy against Maimonides’ view that one of its central features, epicycles, is fundamentally at odds with the principles of Aristotelian motion. In doing so, he is drawing on Gersonides’ exceptionally thorough discussion of the objections to epicycles in his Wars of the Lord.45 Another objection to Ptolemaic astronomical systems adduced by Maimonides in this same chapter concerns the issue of how the epicycles can move in reality without transferring their motion to the spheres they touch—if, as assumed, there is no vacuum in space. Again in Wars of the Lord, Gersonides posits a substance—a fluid left over from creation—that he calls “the body that does not keep its shape,” and in his gloss Duran invokes this celestial matter, in Gersonides’ name, as another answer to Maimonides.46
In Guide II.24, Maimonides seems to note with some resignation that the most we can know about the heavens is “a tiny part of what is mathematical.” Duran, however, might interpret Maimonides’ assertion as said not resignedly but optimistically; we may not be able to know the essence and nature of the celestial realms, because we cannot touch them or experience them directly, but we can construct mathematical models of them that tell us something about their Creator, and we can speculate about them with our intellects in a constructive way.
Scholars today are divided on the issue of Maimonides’ view of the knowability of the celestial realms and its ultimate consequences for our ability to know the divine,47 but Duran does not hesitate to attribute to Maimonides the “skeptical” view that the separate intellects are beyond human apprehension, even for Moses. When Maimonides in Guide I.54 asserts that Moses “grasped the existence of all [God’s] world with a true and firmly established understanding,” Duran interprets this to mean that “Moses our master did not apprehend perfectly the separate intellects; even the agent intellect he did not apprehend perfectly, for it is permitted to corporeal beings only to apprehend the existence of His world, that is to say, the corporeal [world]; to apprehend the essence of the matter of the celestial sphere is something that is not within the power of any sage or philosopher.”48
With respect to knowledge of the sublunar world, Duran’s comments seem to bring Maimonides closer to Gersonides. As Duran formulates the point, with some caveats, “If you wish to apprehend that He is the principle of all existent things, persevere and contemplate and intelligize all existents. Then you will know demonstratively that the Lord is the principle of all existents and you will apprehend Him as much as you are able to apprehend, for knowledge of His essence is impossible. Therefore, whoever wishes to apprehend Him, as much as can be apprehended, let him apprehend and intelligize all the particulars of existents. And according to what he intelligizes of the particulars of the existent things, he will intelligize Him, for all existents are stamped by Him, with a spiritual, formal stamp.”49 As the potter leaves the marks of his fingers in the clay, God has left his stamp in every detail of his creation. By examining these details, the forms of the world, one can learn something about the Maker. By apprehending the “spiritual, formal stamp” of the world, one can, to some limited extent, apprehend God. In this, Duran may be reflecting the position of Gersonides, who held that man can come to know natural laws through his sensory experience. While God knows these laws a priori, natural laws produce the individual events from which man can then deduce the laws.50 And those laws can tell us something about God.
But what about the laws expressed by the divine governance of the earth by means of the celestial realm? Can they tell us anything about God? Maimonides calls on the reader to consider the enormous size of the universe (“this great and terrifying distance”),51 arguing that the remoteness of the orb of the fixed stars is indicative of the still greater remoteness of God. If we are at so great a distance from the body of the highest part of the orb of Saturn that “its substance and most of its actions are hidden from us,” how much more can this be said of God, “Who is not a body”?52 In his gloss, however, Duran asserts: “Its substance is hidden from us: he means that the substances [essences] of the spheres cannot be apprehended through the senses, only through the intellect. Most of its actions [are hidden from us]: i.e. apprehension of the actions of the heavenly bodies in this lower world, most of them are hidden from us. How much more can this be said of God: He means that [if] apprehension of the actions of the heavenly bodies is hidden from us, all the more so is it proper [to say] that the apprehension of the actions of their agent, which is not a body, and [apprehension] of Him, may He be blessed, are hidden.”53
Duran allows that while we may not be able to apprehend the orb of Saturn with our material senses, we can apprehend its existence, and some of its actions, with our intellect. I understand him to mean that Saturn is so far away we can barely see it, and its motion is so slow as to be hardly detectable. We certainly cannot “see” its celestial sphere. But its existence can be apprehended with the intellect through observation of the phenomena—in particular, I would suggest, by constructing mathematical models for its motion. As for Saturn’s “actions,” it would appear that Duran is interpreting Maimonides’ words as referring not to the planet’s motions but to its influence on the lower world. What we have here is a causal chain: God “moves” the intellects, the intellects “move” the spheres and their planets, and the planets “move” the terrestrial elements. Maimonides would then be saying (in Duran’s interpretation) that since we do not fully understand the workings of the influences of the planets on this earth, how much less can we understand the workings of their causes, or of the First Cause; but from what we do observe, we can use our intellects to construct arguments about their existence. It is, however, precisely the workings of the influences of the planets on the earth that is the “esoteric” subject of the Account of the Chariot described above.
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