This new beginning of our discussion of the universe requires a fuller division than the former ; for then we made two classes, now a third must be revealed. The two sufficed for the former discussion : one, which we assumed, was a pattern intelligible and always the same ; and the second was only the imitation of the pattern, generated and visible. There is also a third kind which we did not distinguish at the time, conceiving that the two would be enough. But now the argument seems to require that we should set forth in words another kind, which is difficult of explanation and dimly seen. What nature are we to attribute to this new kind of being ? We reply, that it is the receptacle, and in a manner the nurse, of all generation. I have spoken the truth ; but I must express myself in clearer language, and this will be an arduous task for many reasons, and in particular because I must first raise questions concerning fire and the other elements, and determine what each of them is ; for to say, with any probability or certitude, which of them should be called water rather than fire, and which should be called any of them rather than all or some one of them, is a difficult matter. How, then, shall we settle this point, and what questions about the elements may be fairly raised ?
In the first place, we see that what we just now called water, by condensation, I suppose, becomes stone and earth ; and this same element, when melted and dispersed, passes into vapour and air. Air, again, when inflamed, becomes fire ; and again fire, when condensed and extinguished, passes once more into the form of air ; and once more, air, when collected and condensed, produces cloud and mist ; and from these, when still more compressed, comes flowing water, and from water comes earth and stones once more ; and thus generation appears to be transmitted from one to the other in a circle. Thus, then, as the several elements never present themselves in the same form, how can any one have the assurance to assert positively that any of them, whatever it may be, is one thing rather than another ? No one can. But much the safest plan is to speak of them as follows : — Anything which we see to be continually changing, as, for example, fire, we must not call “this” or “that,” but rather say that it is “of such a nature” ; nor let us speak of water as “this” ; but always as “such” ; nor must we imply that there is any stability in any of those things which we indicate by the use of the words “this” and “that,” supposing ourselves to signify something thereby ; for they are too volatile to be detained in any such expressions as “this,” or “that,” or “relative to this,” or any other mode of speaking which represents them as permanent. We ought not to apply “this” to any of them, but rather the word “such” ; which expresses the similar principle circulating in each and all of them ; for example, that should be called “fire” which is of such a nature always, and so of everything that has generation. That in which the elements severally grow up, and appear, and decay, is alone to be called by the name “this” or “that” ; but that which is of a certain nature, hot or white, or anything which admits of opposite equalities, and all things that are compounded of them, ought not to be so denominated. Let me make another attempt to explain my meaning more clearly. Suppose a person to make all kinds of figures of gold and to be always transmuting one form into all the rest — somebody points to one of them and asks what it is. By far the safest and truest answer is, That is gold ; and not to call the triangle or any other figures which are formed in the gold “these,” as though they had existence, since they are in process of change while he is making the assertion ; but if the questioner be willing to take the safe and indefinite expression, “such,” we should be satisfied. And the same argument applies to the universal nature which receives all bodies — that must be always called the same ; for, while receiving all things, she never departs at all from her own nature, and never in any way, or at any time, assumes a form like that of any of the things which enter into her ; she is the natural recipient of all impressions, and is stirred and informed by them, and appears different from time to time by reason of them. But the forms which enter into and go out of her are the likenesses of real existences modelled after their patterns in wonderful and inexplicable manner, which we will hereafter investigate. For the present we have only to conceive of three natures : first, that which is in process of generation ; secondly, that in which the generation takes place ; and thirdly, that of which the thing generated is a resemblance. And we may liken the receiving principle to a mother, and the source or spring to a father, and the intermediate nature to a child ; and may remark further, that if the model is to take every variety of form, then the matter in which the model is fashioned will not be duly prepared, unless it is formless, and free from the impress of any of these shapes which it is hereafter to receive from without. For if the matter were like any of the supervening forms, then whenever any opposite or entirely different nature was stamped upon its surface, it would take the impression badly, because it would intrude its own shape. Wherefore, that which is to receive all forms should have no form ; as in making perfumes they first contrive that the liquid substance which is to receive the scent shall be as inodorous as possible ; or as those who wish to impress figures on soft substances do not allow any previous impression to remain, but begin by making the surface as even and smooth as possible. In the same way that which is to receive perpetually and through its whole extent the resemblances of all eternal beings ought to be devoid of any particular form. Wherefore, the mother and receptacle of all created and visible and in any way sensible things, is not to be termed earth, or air, or fire, or water, or any of their compounds or any of the elements from which these are derived, but is an invisible and formless being which receives all things and in some mysterious way partakes of the intelligible, and is most incomprehensible. In saying this we shall not be far wrong ; as far, however, as we can attain to a knowledge of her from the previous considerations, we may truly say that fire is that part of her nature which from time to time is inflamed, and water that which is moistened, and that the mother substance becomes earth and air, in so far as she receives the impressions of them.