Timaeus explains why, on his view, man is the sort of being he is by nature. He tells of the creative activity of the Demiurge:
Ταῦτ΄ εἶπε͵ καὶ πάλιν ἐπὶ τὸν πρότερον κρατῆρα͵ ἐν ᾧ τὴν τοῦ παντὸς ψυχὴν κεραννὺς ἔμισγεν͵ τὰ τῶν πρόσθεν ὑπόλοιπα κατεχεῖτο μίσγων τρόπον μέν τινα τὸν αὐτόν͵ ἀκήρατα δὲ οὐκέτι κατὰ ταὐτὰ ὡσαύτως͵ ἀλλὰ δεύτερα καὶ τρίτα. συστήσας δὲ τὸ πᾶν διεῖλεν ψυχὰς ἰσαρίθμους τοῖς ἄστροις͵ [41e] ἔνειμέν θ΄ ἑκάστην πρὸς ἕκαστον͵ καὶ ἐμβιβάσας ὡς ἐς ὄχημα τὴν τοῦ παντὸς φύσιν ἔδειξεν͵ νόμους τε τοὺς εἱμαρμένους εἶπεν αὐταῖς͵ ὅτι γένεσις πρώτη μὲν ἔσοιτο τεταγμένη μία πᾶσιν͵ ἵνα μήτις ἐλαττοῖτο ὑπ΄ αὐτοῦ͵ δέοι δὲ σπαρείσας αὐτὰς εἰς τὰ προσήκοντα ἑκάσταις ἕκαστα ὄργανα χρόνων φῦναι ζῴων τὸ θεοσεβέστατον….
Thus he spake, and once more into the cup in which he had previously mingled the soul of the universe he poured the remains of the elements, and mingled them in much the same manner; they were not, however, pure as before, but diluted to the second and third degree. And having made it he divided the whole mixture into souls equal in number to the stars, and assigned each soul to a star; and having there placed them as in a chariot, he showed them the nature of the universe, and declared to them the laws of destiny, according to which their first birth would be one and the same for all,-no one should suffer a disadvantage at his hands; they were to be sown in the instruments of time severally adapted to them, and to come forth the most religious of animals…. (Plato, Timaeus 41e)
The details, of course, strike the Christian as odd (and also untrue), but the observation about man’s fundamentally religious nature is acute–thus it is used by Turretin early on in his Institutes of Elenctic Theology as a sort of proof-text for the existence of a natural theology.