Lecture 2 — Opinions of the ancients on the generation of things

407 Earlier speculation was at variance both with itself and with the views here put forward as to the true answer to this question.

408 Some removed generation and destruction from the world altogether. Nothing that is, they said, is generated or destroyed, and our conviction to the contrary is an illusion. So maintained the school of Melissus and Parmenides. But however excellent their theories may otherwise be, anyhow they cannot be held to speak as students of nature. There may be things not subject to generation or any kind of movement, but if so they belong to another and a higher inquiry than the study of nature. They, however, had no idea of any form of being other than the substance of things perceived; and when they saw, what no one previously had seen, that there could be no knowledge or wisdom without some such unchanging entities, they naturally transferred what was true of them to things perceived.

409 Others, perhaps intentionally, maintain precisely the contrary opinion to this. It has been asserted that everything in the world was subject to generation and nothing was ungenerated, but that after being generated some things remained indestructible while the rest were again destroyed. This had been asserted in the first instance by Hesiod and his followers,

410 but afterwards outside his circle by the earliest natural philosophers. But what these thinkers maintained was that all else has been generated and, as they said, 'is flowing away, nothing having any solidity, except one single thing which persists as the basis of all these transformations. So we may interpret the statements of Heraclitus of Ephesus and many others.

411 And some subject all bodies whatever to generation, by means of the composition and separation of planes.

551. Having presented an introduction in which he showed what remains to be considered in natural science, he now undertakes to pursue what has been said.

First, by inquiring into the opinions of philosophers on this matter;

secondly, by determining the truth, at de gravi autem et levi in book IV.

About the first he does two things:

first, he inquires into the generation and motion of natural bodies, as to whether it exists;

secondly, as to which things are generated and moved, and why, at from what has been said earlier it is plain (L. 8; 301b31).

Concerning the first he does two things:

first, he inquires according to the opinions of early philosophers whether generation is a fact;

secondly, whether local motion is natural to natural bodies, at the necessity that each of the simple bodies (L. 5; 300a20).

As to the first he does two things:

first he cites the opinions of the ancients about generation;

secondly, he investigates the truth of these opinions, at discussion of the other views (L. 3; 299a1).

Regarding the first he does three things:

first he shows the difference among philosophers as to generation;

secondly, he presents the opinions that deny generation, at some removed generation and destruction (298b14; [552]);

thirdly, those that attribute generation to bodies, at others, perhaps intentionally (298b24; [554]).

He says therefore first (298b12) that those who previously philosophized about the truth, namely, speculative truth (which he says to distinguish them from those who philosophized on morals and on politics), are in their opinions both at variance with one another and with what will now be said about generation.

552. Then, at some removed generation and destruction (298b14), he presents the opinions of those who remove generation. And he says that certain of the ancient philosophers totally removed generation and decay from things—for they said that nothing in beings comes to be or is destroyed, but something only seems to us to be generated or destroyed. This was the opinion of the followers of Melissus and Parmenides, whom Aristotle in one respect praises and in another condemns. He praises them for being the first to recognize that there have to be natures that are ungenerated and indestructible and immobile. This they were moved to assert for the reason that there cannot be sure knowledge or science about things that are subject to generation and decay. If, then, there is any certain knowledge or science, there must be certain natures which are ungenerated and indestructible. For even if there be some science of the things subject to generation and decay, it is only insofar as there is in them something ungenerated and indestructible, according to a participation in those natures that of themselves are ungenerated and indestructible. For they are known according to their forms, and form is something divine in things, insofar as it is a participation of the first act. But Aristotle reprehends them because, since they supposed that nothing beyond what can be sensed exists, and yet understood that there have to be certain ungenerated and indestructible substances, they transferred what belongs to the notion of the substances above nature to these sensible things, stating these sensible things to be in truth ungenerated and indestructible, but to be generated and destroyed according to opinion. But it is manifest that if there are certain ungenerated and indestructible and utterly immobile beings, their study does not pertain to natural philosophy, which is wholly concerned with changeable things, but pertains more to another prior philosophy, which is metaphysics. And therefore Parmenides and Melissus, although they spoke well in one respect, by positing the need for something ungenerated and immobile to exist, nevertheless did not speak well in treating of natural things in a non-natural way, attributing the qualities of immobile substances to natural substances, which are sensible substances.

553. But Simplicius in his commentary says that Aristotle in his customary way reprehends Parmenides and Melissus for what externally appeared from their words lest anyone, understanding them superficially, should be deceived, but that in fact the intention of these philosophers was that being of itself, i.e., being that exists by its very essence, is ungenerated and indestructible and completely unchangeable. As to their statement that generation and decay are in things only according to opinion and not in reality, this they said because they believed that sensible things, in which generation and decay are found, are not truly beings but only according to opinion.

554. Then, at others, perhaps intentionally (298b24) he presents the opinion of those who attribute generation to bodies, and he gives three opinions.

He says that certain others held an opinion contrary to the foregoing, as though purposely intending to contradict them. For some maintain that nothing is ungenerated but that all things are generated, and that among these some remain indestructible and others are destroyed. Such was the doctrine especially of the followers of Hesiod, one of the Theologizing Poets, who treated divine matters under the guise of fables. Hence, Hesiod is said to have posited even chaos, from which all things are generated, to have been generated. But whatever is generated is generated by some generator. Hence they gave it out that over all those things there is a certain first cause, namely, an intellect and a divinity, from which all things proceeded. Such a procession of all things from the first principle they called "generation."

555. The second opinion is given at but afterwards outside his circle (298b29). And he says that after the afore-said poets, among others who first treated of nature, were those who maintained that all other things are generated and remain in a state of continuous flux, so that nothing is fixed and permanent in things except one, namely, the material principle which underlies all things that come to be and decay. This same thing was maintained by many other philosophers—such as Thales, who proposed that water is this first principle; and Anaxagoras, air; but Anaximander, an intermediate between the two, namely, vapor. Heraclitus of Ephesus proposed fire (and is specially mentioned because he more than others asserted all things to be in continual flux).

556. The third opinion he gives at and some subject all bodies whatever (298b33). And he says that there are some who maintained every body is generable because they posit that all bodies are composed of surfaces and are reducible to surfaces. This was Plato's opinion.