Plato’s Timaeus. Folio XII.

...by reason: and a fraud to all eloquence, enveloped in thick darkness.

¶ What power, then, or what nature must we think it possesses? I believe it is the receptacle original: receptaculum; Plato’s term for the "space" or "matrix" in which things are formed of all things that are born: and like a certain nurse original: nutricula; a metaphor for the supporting role of matter. And indeed, what is said of it is true: but it seems necessary to speak a little more clearly. Yet it is difficult, all the more because the edge of the mind must necessarily be confused and in a state of flux, as much concerning fire as the other materials; for which of them ought more rightly to be called and thought of as water than as earth? Since there is no certain and stable property of bodies which might indicate the natural kinship of each.

Water.

Air.

¶ To begin, let us start with water, which we just mentioned: when it is bound into ice, it certainly appears as a stone and a body of earthy solidity, and not at all fluid. This same substance, when heated and flowing and variously dispersed, dissolves into moisture, spirit, and airy breezes. Furthermore, air, when burnt up, creates fire. Conversely, when fire is extinguished, it is restored as air, having become more corporeal. Likewise, when air becomes thicker, it congeals into clouds and mists. When these are crushed and squeezed out, an abundance of rain, pools, and springs results, and finally, earthy masses are heaped up from the water. And so, in a certain circuit, the powers and nourishments of generation are borrowed by bodies from one another in turn: and since they do not persist in one and the same form, what certain comprehension of them can there be, removed from hesitation? Certainly none. Therefore, concerning all such changeable things, it must be held thus: That which often appears to us formed in one way or another, and mostly in the likeness of fire, is not, I believe, fire, but something fiery; nor is it air, but something airy; nor is it anything at all that has any stability. Finally, they are not even worthy of any pronouns which we are accustomed to use in demonstration, such as when we say "this" or "that." For they flee and do not wait for that designation which is held concerning them as if they were existing things. Therefore, we must think that fire is truly that which is always the same: and everything whose property remains. But indeed, that in which each of these things is seen to come to be, and finally to dissolve and, perishing, to pass from there into other forms—I think only that should be called by a certain pronoun. For it can rightly be said of it, "this" or "that." Furthermore, that which receives a quality—or can even be turned into contrary qualities, such as hot or white—it is not at all fitting to call by a proper and certain name that which is uncertain and changeable. But I think even now we must attempt to discourse more clearly on the same subject.

† it departs from.

¶ For if someone were to reshape all forms and figures made from one and the same material of gold, continually and without intermission into one form after another: then if someone, having chosen any one figure, should ask what it is: I believe it could be answered firmly, diligently, and without reproach, that it is gold; nor will it seem right to add that it is a triangle, a cylinder, or any other form. The same and similar reasoning and difficulty is found in that nature which receives all bodies. For this nature least of all † departs from its own condition. For it receives all things: nor does it draw any form from them: and while those things which it receives are formed as if within its womb, it remains itself formless: and its use is similar to a soft and yielding material into which various marks are impressed; and it is moved and shaped in every way by the things entering it, having itself neither form nor motion from its own nature. But those things which enter change the forms, and some are seen as different from others: and those very things which enter and depart are images original: simulachra; reflections or copies of the eternal Forms of truly existing things: formed in a marvelous and scarcely explainable way: from those same existing things: just as we shall soon avoid no effort to demonstrate.

¶ But now, I say, a threefold genus must be assumed: which...