Now there's no doubt that φρενες means "diaphragm" in Hippocrates. The text is very intelligent and contains many acute observations on the normal and abnormal functioning of the brain, especially epilepsy - and, what's most important, the actual observation that the brain is behind all this. However, since the text was written something like 400 BC, there are some misconceptions - some of which Hippocrates shares with Homer. One of them is what breathing air does to us: both basically think that air is a vital substance that provides us with intellect - Homer calls it θυμος, Hippocrates αηρ.
This is the earlier post: http://www.textkit.com/greek-latin-foru ... 22&t=63041
On the Holy Disease, section 16:
κατὰ ταῦτα νομίζω τὸν ἐγκέφαλον δύναμιν πλείστην ἔχειν ἐν τῷ ἀνθρώπῳ: οὗτος γὰρ ἡμῖν ἐστι τῶν ἀπὸ τοῦ ἠέρος γινομένων ἑρμηνεὺς, ἢν ὑγιαίνων τυγχάνῃ: τὴν δὲ φρόνησιν αὐτῷ ὁ ἀὴρ παρέχεται.
οἱ δὲ ὀφθαλμοὶ καὶ τὰ οὔατα καὶ ἡ γλῶσσα καὶ αἱ χεῖρες καὶ οἱ πόδες οἷα ἂν ὁ ἐγκέφαλος γινώσκῃ, τοιαῦτα πρήσσουσι: γίνεται γὰρ παντὶ τῷ σώματι τῆς φρονήσιος, ὡς ἂν μετέχῃ τοῦ ἠέρος.
ἐς δὲ. τὴν ξύνεσιν ὁ ἐγκέφαλός ἐστιν ὁ διαγγέλλων: ὁκόταν γὰρ σπάσῃ τὸ πνεῦμα ὥνθρωπος ἐς ἑωυτὸν, ἐς τὸν ἐγκέφαλον πρῶτον ἀφικνέεται, καὶ οὕτως ἐς τὸ λοιπὸν σῶμα σκίδναται ὁ ἀὴρ, καταλιπὼν ἐν τῷ ἐγκεφάλῳ ἑωυτοῦ τὴν ἀκμὴν καὶ ὅ τι ἂν ἔῃ φρόνιμόν τε καὶ γνώμην ἔχον: εἰ γὰρ ἐς τὸ σῶμα πρῶτον ἀφικνέετο καὶ ὕστερον ἐς τὸν ἐγκέφαλον, ἐν τῇσι σαρξὶ καὶ ἐν τῇσι φλεψὶ καταλελοιπὼς τὴν
διάγνωσιν ἐς τὸν ἐγκέφαλον ἂν ἴοι θερμὸς ἐὼν καὶ οὐχὶ ἀκραιφνὴς, ἀλλ᾽ ἐπιμεμιγμένος τῇ ἰκμάδι τῆ ἀπὸ τῶν σαρκῶν καὶ τοῦ αἵματος, ὥστε μηκέτι εἶναι ἀκριβής.
In these ways I am of the opinion that the brain exercises the greatest power in the man. This is the interpreter to us of those things which emanate from the air, when it (the brain) happens to be in a sound state. But the air supplies sense to it. And the eyes, the ears, the tongue and the feet, administer such things as the brain cogitates. For in as much as it is supplied with air, does it impart sense to the body. It is the brain which is the messenger to the understanding. For when the man draws the breath (pneuma) into himself, it passes first to the brain, and thus the air is distributed to the rest of the body, leaving in the brain its acme, and whatever has sense and understanding. For if it passed first to the body and last to the brain, then having left in the flesh and veins the judgment, when it reached the brain it would be hot, and not at all pure, but mixed with the humidity from flesh and blood, so as to be no longer pure.