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. 

εἰ γὰρ πάντα τις σχήματα πλάσας ἐκ χρυσοῦ μηδὲν μεταπλάττων παύοιτο ἕκαστα εἰς ἅπαντα͵ δεικνύντος δή τινος αὐτῶν ἓν καὶ ἐρομένου τί ποτ΄ ἐστί͵ [50b] μακρῷ πρὸς ἀλήθειαν ἀσφαλέστατον εἰπεῖν ὅτι χρυσός͵ τὸ δὲ τρίγωνον ὅσα τε ἄλλα σχήματα ἐνεγίγνετο͵ μηδέποτε λέγειν ταῦτα ὡς ὄντα͵ ἅ γε μεταξὺ τιθεμένου μεταπίπτει͵ ἀλλ΄ ἐὰν ἄρα καὶ τὸ τοιοῦτον μετ΄ ἀσφαλείας ἐθέλῃ δέχεσθαί τινος͵ ἀγαπᾶν. ὁ αὐτὸς δὴ λόγος καὶ περὶ τῆς τὰ πάντα δεχομένης σώματα φύσεως. ταὐτὸν αὐτὴν ἀεὶ προσρητέον· ἐκ γὰρ τῆς ἑαυτῆς τὸ παράπαν οὐκ ἐξίσταται δυνάμεως [50c] - δέχεταί τε γὰρ ἀεὶ τὰ πάντα͵ καὶ μορφὴν οὐδεμίαν ποτὲ οὐδενὶ τῶν εἰσιόντων ὁμοίαν εἴληφεν οὐδαμῇ οὐδαμῶς· ἐκμαγεῖον γὰρ φύσει παντὶ κεῖται͵ κινούμενόν τε καὶ διασχηματιζόμενον ὑπὸ τῶν εἰσιόντων͵ φαίνεται δὲ δι΄ ἐκεῖνα ἄλλοτε ἀλλοῖον - τὰ δὲ εἰσιόντα καὶ ἐξιόντα τῶν ὄντων ἀεὶ μιμήματα͵ τυπωθέντα ἀπ΄ αὐτῶν τρόπον τινὰ δύσφραστον καὶ θαυμαστόν͵ ὃν εἰς αὖθις μέτιμεν. ἐν δ΄ οὖν τῷ παρόντι χρὴ γένη διανοηθῆναι τριττά͵ [50d] τὸ μὲν γιγνόμενον͵ τὸ δ΄ ἐν ᾧ γίγνεται͵ τὸ δ΄ ὅθεν ἀφομοιούμενον φύεται τὸ γιγνόμενον. καὶ δὴ καὶ προσεικάσαι πρέπει τὸ μὲν δεχόμενον μητρί͵ τὸ δ΄ ὅθεν πατρί͵ τὴν δὲ μεταξὺ τούτων φύσιν ἐκγόνῳ͵ νοῆσαί τε ὡς οὐκ ἂν ἄλλως͵ ἐκτυπώματος ἔσεσθαι μέλλοντος ἰδεῖν ποικίλου πάσας ποικιλίας͵ τοῦτ΄ αὐτὸ ἐν ᾧ ἐκτυπούμενον ἐνίσταται γένοιτ΄ ἂν παρεσκευασμένον εὖ͵ πλὴν ἄμορφον ὂν ἐκείνων ἁπασῶν τῶν ἰδεῶν ὅσας μέλλοι δέχεσθαί ποθεν. [50e] ὅμοιον γὰρ ὂν τῶν ἐπεισιόντων τινὶ τὰ τῆς ἐναντίας τά τε τῆς τὸ παράπαν ἄλλης φύσεως ὁπότ΄ ἔλθοι δεχόμενον κακῶς ἂν ἀφομοιοῖ͵ τὴν αὑτοῦ παρεμφαῖνον ὄψιν. διὸ καὶ πάντων ἐκτὸς εἰδῶν εἶναι χρεὼν τὸ τὰ πάντα ἐκδεξόμενον ἐν αὑτῷ γένη͵ καθάπερ περὶ τὰ ἀλείμματα ὁπόσα εὐώδη τέχνῃ μηχανῶνται πρῶτον τοῦτ΄ αὐτὸ ὑπάρχον͵ ποιοῦσιν ὅτι μάλιστα ἀώδη τὰ δεξόμενα ὑγρὰ τὰς ὀσμάς· ὅσοι τε ἔν τισιν τῶν μαλακῶν σχήματα ἀπομάττειν ἐπιχειροῦσι͵ τὸ παράπαν σχῆμα οὐδὲν ἔνδηλον ὑπάρχειν ἐῶσι͵ προομαλύναντες δὲ ὅτι λειότατον ἀπεργάζονται. [51a] ταὐτὸν οὖν καὶ τῷ τὰ τῶν πάντων ἀεί τε ὄντων κατὰ πᾶν ἑαυτοῦ πολλάκις ἀφομοιώματα καλῶς μέλλοντι δέχεσθαι πάντων ἐκτὸς αὐτῷ προσήκει πεφυκέναι τῶν εἰδῶν. διὸ δὴ τὴν τοῦ γεγονότος ὁρατοῦ καὶ πάντως αἰσθητοῦ μητέρα καὶ ὑποδοχὴν μήτε γῆν μήτε ἀέρα μήτε πῦρ μήτε ὕδωρ λέγωμεν͵ μήτε ὅσα ἐκ τούτων μήτε ἐξ ὧν ταῦτα γέγονεν· [51b] ἀλλ΄ ἀνόρατον εἶδός τι καὶ ἄμορφον͵ πανδεχές͵ μεταλαμβάνον δὲ ἀπορώτατά πῃ τοῦ νοητοῦ καὶ δυσαλωτότατον αὐτὸ λέγοντες οὐ ψευσόμεθα. καθ΄ ὅσον δ΄ ἐκ τῶν προειρημένων δυνατὸν ἐφικνεῖσθαι τῆς φύσεως αὐτοῦ͵ τῇδ΄ ἄν τις ὀρθότατα λέγοι· πῦρ μὲν ἑκάστοτε αὐτοῦ τὸ πεπυρωμένον μέρος φαίνεσθαι͵ τὸ δὲ ὑγρανθὲν ὕδωρ͵ γῆν τε καὶ ἀέρα καθ΄ ὅσον ἂν μιμήματα τούτων δέχηται.