The Fragments on Nature is a modern designation for the surviving doctrines of Alcmaeon of Croton, an early Greek philosopher and physician active in the late sixth or early fifth century BCE. His original prose treatise, often considered the first known Greek medical text, is lost. Its content survives only in a handful of principal fragments preserved through quotation by later philosophers, physicians, and doxographers. These passages address the body, the acquisition of knowledge, and the cosmos. Alcmaeon’s work originated in the intellectual milieu of Croton in southern Italy, a centre for Pythagorean thought. While his precise relationship to the Pythagorean school remains debated by scholars, his inquiries effectively bridged philosophical speculation with empirical observation. His most enduring contribution is the theory that health constitutes a balance, or isonomia, of opposing qualities within the body—such as hot and cold, wet and dry, bitter and sweet—whereas nosos arises from the monarchy, or dominance, of any single one of them. He also broke significant ground by proposing that the brain, rather than the heart, is the central organ of sensation and cognition. Furthermore, he posited that psychē is immortal and in perpetual motion. These theories proved highly influential, directly informing later medical thought in the Hippocratic tradition and sparking enduring ancient debates concerning the seat of perception and the nature of health.
ΑΛΚΜΑΙΩΝΟΣ ΠΕΡΙ ΦΥΣΕΩΣ
Λαέρτιος Διογένης Ἀλκμαίων Κροτωνιήτης 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.
Θεόφραστος ἄνθρωπον γάρ φησι τῶν ἄλλων διαφέρειν ὅτι μόνον ξυνίησι, τὰ δʼ ἄλλα αἰσθάνεται μέν, οὐ ξυνίησι δέ.
Ἀριστοτέλης τοὺς ἀνθρώπους φησὶν Ἀ. διὰ τοῦτο ἀπόλλυσθαι, ὅτι οὐ δύνανται τὴν ἀρχὴν τῶι τέλει προσάψαι.
Ἀέτιος Ἀ. τῶν ἡμιόνων τοὺς μὲν ἄρρενας ἀγόνους παρὰ τὴν λεπτότητα τῆς θορῆς καὶ ψυχρότητα, τὰς δὲ θηλείας παρὰ τὸ μὴ ἀναχάσκειν τὰς μήτρας· οὕτω γὰρ αὐτὸς εἴρηκε.
Ἀ. τῆς μὲν ὑγιείας εἶναι συνεκτικὴν τὴν ἰσονομίαν τῶν δυνάμεων, ὑγροῦ, ξηροῦ, ψυχροῦ, θερμοῦ, πικροῦ, γλυκέος καὶ τῶν λοιπῶν, τὴν δʼ ἐν αὐτοῖς μοναρχίαν νόσου ποιητικήν· φθοροποιὸν γὰρ ἑκατέρου μοναρχίαν. καὶ νόσον συμπίπτειν ὡς μὲν ὑφʼ οὗ ὑπερβολῆι θερμότητος ἢ ψυχρότητος, ὡς δὲ ἐξ οὗ διὰ πλῆθος τροφῆς ἢ ἔνδειαν, ὡς δʼ ἐν οἷς ἢ … αἷμα ἢ μυελὸν ἢ ἐγκέφαλον. ἐγγίνεσθαι δὲ τούτοις ποτὲ κἀκ τῶν ἔξωθεν αἰτιῶν, ὑδάτων ποιῶν … ἢ χώρας ἢ κόπων ἢ ἀνάγκης ἢ τῶν τούτοις παραπλησίων. τὴν δὲ ὑγείαν τὴν σύμμετρον τῶν ποιῶν κρᾶσιν.
Κλήμης ὁ Ἀλεξανδρεύς Ἀλκμαίωνος γὰρ τοῦ Κροτωνιάτου λέγοντος «ἐχθρὸν ἄνδρα ῥᾶιον φυλάξασθαι ἢ φίλον» ὁ μὲν Σοφοκλῆς ἐποίησεν ἐν τῆι Ἀντιγόνηι «τί γὰρ γένοιτʼ ἂν ἕλκος μεῖζον ἢ φίλος κακός;».
