Arist. _Met._ Α, 5. 986 a 27 (R. P. 66). In a 30 Diels reads, with great probability, ἐγένετο τὴν ἡλικίαν <νέος> ἐπὶ γέροντι Πυθαγόρᾳ. Cf. Iambl. _V. Pyth._ 104, where Alkmaion is mentioned among the συγχρονίσαντες καὶ μαθητεύσαντες τῷ Πυθαγόρᾳ πρεσβύτῃ νέοι. Footnote 489: Ἀλκμαίων Κρωτωνιήτης τάδε ἔλεξε Πειρίθου υἱὸς Βροτίνῳ καὶ Λέοντι καὶ Βαθύλλῳ· περὶ τῶν ἀφανέων, περὶ τῶν θνητῶν, σαφήνειαν μὲν θεοὶ ἔχοντι, ὡς δὲ ἀνθρώποις τεκμαίρεσθαι καὶ τὰ ἑξῆς. The fact that this is not written in conventional Doric, like the forged Pythagorean books, is a strong proof of genuineness. Footnote 490: Brotinos (not Brontinos) is variously described as the son-in-law or father-in-law of Pythagoras. Leon is one of the Metapontines in the catalogue of Iamblichos (Diels, _Vors._ p. 268), and Bathyllos is presumably the Poseidoniate Bathylaos also mentioned there. Alkmaion’s chief importance in the history of philosophy really lies in the fact that he is the founder of empirical psychology.[491] It is certain that he regarded the brain as the common sensorium, an important discovery which Hippokrates and Plato adopted from him, though Empedokles, Aristotle, and the Stoics reverted to the more primitive view that the heart performs this function. There is no reason to doubt that he made this discovery by anatomical means. We have some authority for saying that he practised dissection, and, though the nerves were not yet recognised as such, it was known that there were certain “passages” which might be prevented from communicating sensations to the brain by lesions.[492] He also distinguished between sensation and understanding, though we have no means of knowing exactly where he drew the line between them. His theories of the special senses are of great interest. We find in him already, what is characteristic of Greek theories of vision as a whole, the attempt to combine the view of vision as an act proceeding from the eye with that which attributes it to an image reflected in the eye. He knew the importance of air for the sense of hearing, though he called it the void, a thoroughly Pythagorean touch. With regard to the other senses, our information is more scanty, but sufficient to show that he treated the subject systematically.[493] Footnote 491: Everything bearing on the early history of this subject is brought together and discussed in Prof. Beare’s _Greek Theories of Elementary Cognition_, to which I must refer the reader for all details. Footnote 492: Theophr. _de sens._ 26 (Beare, p. 252, n. 1). Our authority for the dissections of Alkmaion is only Chalcidius, but he gets his information on such matters from far older sources. The πόροι and the inference from lesions are vouched for by Theophrastos. Footnote 493: The details will be found in Beare, pp. 11 sqq. (vision), pp. 93 sqq. (hearing), pp. 131 sqq. (smell), pp. 180 sqq. (touch), pp. 160 sqq. (taste).