PHILOPONI IN PHYSICORUM I 1 [Arist. p. 184 a 10]

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So much for the things that accompany natural objects. In the first book, he refutes the opinions of the ancients concerning natural principles and teaches about form and matter. In the second, he teaches about form (though he also discusses matter, just as he discussed form in the first; but he discusses matter more in the first than form, just as he discusses form more in the second than matter). In the third, he teaches about motion and the infinite; in the fourth, about place, time, and the void; and in the remaining four, about motion and all things that accompany it. Indeed, Aristotle himself, when he wishes to refer to these books, says, "It has been said by us in On Motion."

p. 184 a 10

It is Aristotle's custom to begin his treatises from certain common axioms. Thus, in the Metaphysics, he began from a common admission: "All men by nature desire to know. A sign of this is the love of the senses." And in the Posterior Analytics: "All instruction and all learning occur from pre-existing knowledge." And in the Ethics: "Every art and every inquiry, and similarly every action and choice, seems to aim at some good." Thus, he makes his beginning here from a common axiom. The axiom is as follows: every science possessing principles, causes, or elements is known once the principles, causes, and elements are known. Since, he says, there are principles, causes, and elements of natural things, we will know them when we know their principles, causes, and elements. The entire syllogism is as follows: The science concerning nature has principles, causes, and elements; every science for which there are principles, causes, or elements is known once the principles, causes, and elements are known; therefore, the science concerning nature will be known once the principles, causes, and elements are known. This is the whole syllogism, but he, for the sake of brevity, set down only the major premise—the one stating that every inquiry for which there are principles, causes, or elements is known [once] the principles, causes, and elements are known—and he omits the minor premise, that there are principles, causes, and elements of physiology.