Plato, Epinomis 981c

σώματι δέ, ὃ λέγομεν, πλάττεσθαι καὶ γίγνεσθαι καὶ ὁρᾶσθαι· τῷ δέ—λέγωμεν πάλιν· οὐ γὰρ ἅπαξ ῥητέον—ἀοράτῳ τε εἶναι καὶ γιγνώσκοντι νοητῷ τε, μνήμης μεταλαβόντι λογισμοῦ τε ἐν περιτταῖς τε καὶ ἀρτίαις ἅμα μεταβολαῖς. πέντε οὖν ὄντων τῶν σωμάτων, πῦρ χρὴ φάναι καὶ ὕδωρ εἶναι καὶ τρίτον ἀέρα, τέταρτον δὲ γῆν, πέμπτον δὲ αἰθέρα, τούτων δʼ ἐν ἡγεμονίαις ἕκαστον ζῷον πολὺ καὶ παντοδαπὸν ἀποτελεῖσθαι. μαθεῖν δὲ καθʼ ἓν ὧδʼ ἔστιν χρεών. γήινον

whereas the body, as we call it, has that of being fashioned and produced and seen. But the other—let us repeat it, for not once only be it said—has to be invisible even to the inquiring, and merely thought, if he has got a share of memory and reckoning by both odd and even variations. The bodies, then, being five, we must name them as fire, water, and thirdly air, earth fourth, and ether fifth; and by predominance of these are each of the many varieties of creatures perfected. We should learn this by single instances in the following way.