“Nature is an artistic fire proceeding on the way to generation and actively moving out of itself. According to Plato, it is defined differently: nature is divine art; or, nature is a sort of artistic power. A different definition: nature is inflamed pneuma moving out of itself, generating, completing and maintaining the human being in accordance with spermatic powers. Or it is defined in this way: nature is a power moving out of itself, a cause of generation, formation, and completion producing and completing a human being. Nature is said to be mixture, and nature is said to be state. Nature is also said to be a motion in accordance with effort. Nature is said to be the power controlling an animal. It can also be defined in this way: nature is the inflamed pneuma moving out of itself, generating, completing and maintaining a human being in accordance with spermatic principles determining lifetime and size.”

Φύσις ἐστὶ πῦρ τεχνικὸν ὁδῷ βαδίζον εἰς γένεσιν καὶ ἐξ ἑαυτοῦ ἐνεργητικῶς κινούμενον. ἑτέρως κατὰ Πλάτωνα. φύσις ἐστὶ θεία τέχνη. ἢ φύσις ἐστὶν οἵα τεχνικὴ δύναμις. ἑτέρως. φύσις ἐστὶ πνεῦμα ἔνθερμον ἐξ ἑαυτοῦ κινούμενον καὶ κατὰ τὰς σπερματικὰς δυνάμεις γεννῶν τε καὶ τελειοῦν καὶ διατηροῦν τὸν ἄνθρωπον. ἢ οὕτως. φύσις ἐστὶ δύναμις ἐξ ἑαυτῆς κινουμένη, αἰτία γενέσεώς τε καὶ διαπλάσεως καὶ τελειότητος γεννῶσά τε καὶ τελειοῦσα τὸν ἄνθρωπον. φύσις καὶ ἡ κρᾶσις λέγεται, φύσις καὶ ἡ ἕξις. φύσις καὶ ἡ καθ' ὁρμὴν κίνησις. φύσις καὶ ἡ διοικοῦσα τὸ ζῶον δύναμις λέγεται. δύναται δὲ καὶ οὕτως ὁρίσασθαι. φύσις ἐστὶ πνεῦμα ἔνθερμον ἐξ ἑαυτοῦ κινούμενον κατὰ σπερματικοὺς λόγους γεννῶν τε καὶ τελειοῦν καὶ διατηροῦν τὸν ἄνθρωπον ἐν χρόνοις καὶ μεγέθεσιν ὡρισμένους.

Ps.-Galen, Medical Definitions 95 (XIX 371 Kühn)