[1133] Galenus defin. medicae 95 Vol. XIX p. 371 K. φύσις ἐστὶ πῦρ τεχνικὸν ὁδῷ βαδίζον εἰς γένεσιν καὶ ἐξ ἑαυτοῦ ἐνεργητικῶς κινούμενον. — — ἑτέρως· φύσις ἐστὶ πνεῦμα ἔνθερμον ἐξ ἑαυτοῦ κινούμενον καὶ κατὰ τὰς σπερματικὰς δυνάμεις γεννῶν τε καὶ τελειοῦν καὶ διατηροῦν τὸν ἄνθρωπον. Secuntur complures definitiones huius valde similes. φύσις καὶ ἡ κρᾶσις λέγεται, φύσις καὶ ἡ ἕξις, φύσις καὶ ἡ καθ’ ὁρμὴν κίνησις. φύσις καὶ ἡ διοικοῦσα τὸ ζῷον δύναμις λέγεται.