“Of things that come to be, some come to be by nature, some by art, some spontaneously. But everything that comes to be (1) comes to be by something and (2) comes to be from something and (3) comes to be something.”

Τῶν δὲ γιγνομένων τὰ μὲν φύσει γίγνεται τὰ δὲ τέχνῃ τὰ δὲ ἀπὸ ταὐτομάτου, πάντα δὲ τὰ γιγνόμενα ὑπό τέ τινος γίγνεται καὶ ἔκ τινος καὶ τί.

Aristotle, Metaphysics Ζ 7, 1032a12-4

“When I was young, Cebes, I was wonderfully keen on that wisdom which they call natural history, for I thought it was splendid to know the causes of each thing, why each comes to be and why it perishes and why it is. And often, I would turn myself up and down, looking first into questions like these: do living creatures arise when heat and cold take on a kind of decay, as some people used to say?”

ἐγὼ γάρ, ἔφη, ὦ Κέβης, νέος ὢν θαυμαστῶς ὡς ἐπεθύμησα ταύτης τῆς σοφίας ἣν δὴ καλοῦσι περὶ φύσεως ἱστορίαν: ὑπερήφανος γάρ μοι ἐδόκει εἶναι, εἰδέναι τὰς αἰτίας ἑκάστου, διὰ τί γίγνεται ἕκαστον καὶ διὰ τί ἀπόλλυται καὶ διὰ τί ἔστι. καὶ πολλάκις [96β] ἐμαυτὸν ἄνω κάτω μετέβαλλον σκοπῶν πρῶτον τὰ τοιάδε: ἆρ᾽ ἐπειδὰν τὸ θερμὸν καὶ τὸ ψυχρὸν σηπεδόνα τινὰ λάβῃ, ὥς τινες ἔλεγον, τότε δὴ τὰ ζῷα συντρέφεται;

Plato, Phaedo 96a6-b3

“Nothing that is decaying comes to be; rather, what is being concocted does; the process of decay and the thing decaying are residues from what has been concocted. Actually, there isn’t anything that comes to be from the whole (of the material it is made out of), any more than in the case of what has been fashioned by art. For if that were the case, there wouldn’t be any need to produce things. What actually happens is that the useless stuff is removed, in the one case by art, in the other case by nature.

“Animals and plants come to be in earth and in water because in earth there is water, and in water there is pneuma, and in all pneuma, there is psychic heat, and so, in a certain way, all things are full of soul. That’s why they are formed quickly once it has been enveloped.

“When it is enveloped, and when the bodily moisture is heated, it becomes like a frothy bubble. Whether what takes shape is a more or less honourable kind of thing, the difference depends on what envelops the psychic principle. Of this (i.e,. what envelops the psychic principle), the causes are the places and the body which is being enclosed.”

γίγνεται δ' οὐθὲν σηπόμενον ἀλλὰ πεττόμενον· ἡ δὲ σῆψις καὶ τὸ σαπρὸν περίττωμα τοῦ πεφθέντος ἐστίν· οὐθὲν γὰρ ἐκ παντὸς γίγνεται καθάπερ οὐδ' ἐν τοῖς ὑπὸ τῆς τέχνης δημιουργουμένοις – οὐθὲν γὰρ ἂν ἔδει ποιεῖν – νῦν δὲ τὸ μὲν ἡ τέχνη τῶν ἀχρήστων ἀφαιρεῖ, τὸ δ' ἡ φύσις.

Γίγνονται δ' ἐν γῇ καὶ ἐν ὑγρῷ τὰ ζῷα καὶ τὰ φυτὰ διὰ τὸ ἐν γῇ μὲν ὕδωρ ὑπάρχειν ἐν δ' ὕδατι πνεῦμα, ἐν δὲ τούτῳ παντὶ θερμότητα ψυχικήν, ὥστε τρόπον τινὰ πάντα ψυχῆς εἶναι πλήρη· διὸ συνίσταται ταχέως ὁπόταν ἐμπεριληφθῇ.

ἐμπεριλαμβάνεται δὲ καὶ γίγνεται θερμαινομένων τῶν σωματικῶν ὑγρῶν οἷον ἀφρώδης πομφόλυξ. αἱ μὲν οὖν διαφοραὶ τοῦ τιμιώτερον εἶναι τὸ γένος καὶ ἀτιμότερον τὸ συνιστάμενον ἐν τῇ περιλήψει τῆς ἀρχῆς τῆς ψυχικῆς ἐστιν. τούτου δὲ καὶ οἱ τόποι αἴτιοι καὶ τὸ σῶμα τὸ περιλαμβανόμενον.

Aristotle, Generation of Animals, 3.11, 762a13—27

“The cause is similar to that in the case of yeast. For yeast goes from being something small to being big, when the more solid part becomes fluid, and the fluid becomes pneumatized. The psychic heat fashions this in the case of animals, but in the case of the yeast, it is the heat of the humour that was blended with it.”

τὸ δ' αἴτιον παραπλήσιον ὅπερ ἐπὶ τῆς ζύμης· καὶ γὰρ ἡ ζύμη ἐκ μικρᾶς μεγάλη γίγνεται τοῦ μὲν στερεωτέρου ὑγραινομένου τοῦ δ' ὑγροῦ πνευματουμένου. δημιουργεῖ δὲ τοῦτο ἡ τοῦ ψυχικοῦ θερμοῦ φύσις ἐν τοῖς ζῴοις, ἐν δὲ ταῖς ζύμαις ἡ τοῦ χυμοῦ τοῦ συγκραθέντος θερμότης.

Aristotle, Generation of Animals 3.4, 755a14-25