Ἐρατοσθένης δέ φησι, καθὸ καὶ Φαβωρῖνος ἐν τῇ ὀγδόῃ Παντοδαπῆς ἱστορίας παρατίθεται, τοῦτον εἶναι τὸν πρῶτον ἐντέχνως πυκτεύσαντα ἐπὶ τῆς ὀγδόης καὶ τετταρακοστῆς Ὀλυμπιάδος, κομήτην καὶ ἁλουργίδα φοροῦντα· ἐκκριθῆναί τ' ἐκ τῶν παίδων καὶ χλευασθέντα αὐτίκα προσβῆναι τοὺς ἄνδρας καὶ νικῆσαι. δηλοῦν δὲ τοῦτο καὶ τοὐπίγραμμα ὅπερ ἐποίησε Θεαίτητος· Πυθαγόρην τινά, Πυθαγόρην, ὦ ξεῖνε, κομήτην, ᾀδόμενον πύκτην εἰ κατέχεις Σάμιον, Πυθαγόρης ἐγώ εἰμι· τὰ δ' ἔργα μου εἴ τιν' ἔροιο Ἠλείων, φήσεις αὐτὸν ἄπιστα λέγειν.
Diogenes Laertios, The Life of Pythagoras
A History of Science Volume I, by Henry Smith Williams:
Diogenes Laertius tells a story about a youth who, clad in a purple toga, entered the arena at the Olympian games and asked to compete with the other youths in boxing. He was derisively denied admission, presumably because he was beyond the legitimate age for juvenile contestants. Nothing daunted, the youth entered the lists of men, and turned the laugh on his critics by coming off victor. The youth who performed this feat was named Pythagoras. He was the same man, if we may credit the story, who afterwards migrated to Italy and became the founder of the famous Crotonian School of Philosophy; the man who developed the religion of the Orphic mysteries; who conceived the idea of the music of the spheres; who promulgated the doctrine of metempsychosis; who first, perhaps, of all men clearly conceived the notion that this world on which we live is a ball which moves in space and which may be habitable on every side.
A strange development that for a stripling pugilist. But we must not forget that in the Greek world athletics held a peculiar place. The chief winner of Olympian games gave his name to an epoch (the ensuing Olympiad of four years), and was honored almost before all others in the land. A sound mind in a sound body was the motto of the day. To excel in feats of strength and dexterity was an accomplishment that even a philosopher need not scorn. It will be recalled that Aeschylus distinguished himself at the battle of Marathon; that Thucydides, the greatest of Greek historians, was a general in the Peloponnesian War; that Xenophon, the pupil and biographer of Socrates, was chiefly famed for having led the Ten Thousand in the memorable campaign of Cyrus the Younger; that Plato himself was credited with having shown great aptitude in early life as a wrestler. If, then, Pythagoras the philosopher was really the Pythagoras who won the boxing contest, we may suppose that in looking back upon this athletic feat from the heights of his priesthood--for he came to be almost deified--he regarded it not as an indiscretion of his youth, but as one of the greatest achievements of his life. Not unlikely he recalled with pride that he was credited with being no less an innovator in athletics than in philosophy. At all events, tradition credits him with the invention of "scientific" boxing. Was it he, perhaps, who taught the Greeks to strike a rising and swinging blow from the hip, as depicted in the famous metopes of the Parthenon? If so, the innovation of Pythagoras was as little heeded in this regard in a subsequent age as was his theory of the motion of the earth; for to strike a swinging blow from the hip, rather than from the shoulder, is a trick which the pugilist learned anew in our own day.