Metaphysics

​After the philosophies we have described, the system of Plato appeared, following them in most respects, but also having some features peculiar to it as compared with the philosophy of the Italians. For having from his youth first become familiar with Cratylus and with the Heraclitean opinions, that all sensible things are ever in flux and that there is no knowledge about them, he held these views even later. And when Socrates was occupying himself with ethical matters and not at all with nature as a whole, but was seeking the universal in these matters and was the first to fix his thought on definitions, Plato, accepting him for this reason, assumed that this process occurred about other things and not about sensible things; for he thought it impossible that there should be a common definition of any of the sensible things, since they were always changing. He, then, called such entities among things ‘ideas,’ and said that all sensible things were named besides them and according to them; for it was by participation that the many things homonymous with the forms existed. But he only changed the name ‘participation’; for the Pythagoreans say that things exist by ‘imitation’ of numbers, but Plato by ‘participation’, having changed the name. However, what this ‘participation’ or ‘imitation’ of the forms might be, they left to be investigated in common. Further, besides sensible things and forms, he says that there are mathematical objects which exist as intermediates, differing from sensible things in being eternal and motionless, and from forms in that there are many similar ones, whereas each form itself is only one. And since the forms are causes of other things, he thought that the elements of those forms were the elements of all existing things. As matter, then, he thought the ‘great and small’ to be principles, and as substance, the ‘one’; for from those, by participation in the one, the numbers exist. However, that the one is substance, and is not called one as being something else, he said in a manner very similar to the Pythagoreans, and that numbers are the causes of substance to other things, likewise to them. But to make a dyad instead of the unlimited as one, and to make the unlimited from the ‘great and small’, this was peculiar to him. And further, he posits numbers besides sensible things, whereas they say that numbers are the things themselves, and they do not place mathematical objects between them. Therefore, to make the one and numbers besides things, and not like the Pythagoreans, and the introduction of forms occurred because of the inquiry in logoi (for the earlier thinkers did not participate in dialectic). And to make the other nature a dyad was because numbers, except the first ones, could be generated from it naturally as from a kind of mold. Yet the contrary happens; for this is not reasonable. For they make many things out of matter, while the form generates only once, but it is seen that from one matter one table is produced, whereas he who applies the form, though being one, makes many tables. And it is similar with the male and the female; for the latter is filled by one copulation, while the male fills many; yet these are imitations of those principles. Plato, then, defined in this way concerning the matters under inquiry; and it is clear from what has been said that he used only two causes: that of ‘what a thing is’ and that according to matter (for the forms are causes of ‘what a thing is’ to other things, and the one is so to the forms), and what the underlying matter is of which the forms are predicated in the case of sensible things, and the one in the case of forms, namely that this is a dyad, the ‘great and small’. Further, he assigned the cause of well-being and of ill-being to each of the two elements respectively, just as we say some of the earlier philosophers also sought to do, such as Empedocles and Anaxagoras.