What is it that grows?
Ἀπορήσειε δ’ ἄν τις καὶ τί ἐστι τὸ αὐξανόμενον, πότερον ᾧ προστίθεταί τι, οἷον εἰ τὴν κνήμην αὐξάνει, αὕτη μείζων, ᾧ δὲ αὐξάνει, ἡ τροφή, οὔ. Διὰ τί δὴ οὖν οὐκ ἄμφω ηὔξηται; μεῖζον γὰρ καὶ ὃ καὶ ᾧ, ὥσπερ ὅταν μίξῃς οἶνον ὕδατι· ὁμοίως γὰρ πλεῖον ἑκάτερον. Ἢ ὅτι τοῦ μὲν μένει ἡ οὐσία, τοῦ δ’ οὔ, οἷον τῆς τροφῆς, ἐπεὶ καὶ ἐνταῦθα τὸ ἐπικρατοῦν λέγεται ἐν τῇ μίξει, οἷον ὅτι οἶνος· ποιεῖ γὰρ τὸ τοῦ οἴνου ἔργον ἀλλ’ οὐ τὸ τοῦ ὕδατος τὸ συνόλον μίγμα. (I.5, 321a29-321b2)
What grows is that to which the addition is made, not that which is added. "It is only the wine that we say has grown, because it remains exhibiting the power of wine" (Philoponus).