Philostratus, Gymnasticus 27
“And there is also a notion older than this which seemed right to Lykourgos for Sparta. Because he meant to provide warrior-athletes for Sparta, he said, “Let the girls exercise and permit them to run in public. Certainly this strengthening of their bodies was for the sake of good childbearing and that they would have better offspring.
For one who comes from this training to her husband’s home will not hesitate to carry water or to mill grain because she has prepared from her youth. And if she is joined together with a youth who has joined her in rigorous exercise, she will provide better offspring—for they will be tall, strong and rarely sick. Sparta became so preeminent in war once her marriages were prepared in this way.”
Καίτοι καὶ πρεσβύτερον τούτου, ὃ καὶ Λυκούργῳ ἐδόκει τῷ Σπαρτιάτῃ· παριστάμενος γὰρ τῇ Λακεδαίμονι πολεμικοὺς ἀθλητὰς, “γυμναζέσθων,” φησὶν, “αἱ κόραι καὶ ἀνείσθων δημοσίᾳ τρέχειν.” ὑπὲρ εὐπαιδίας δήπου καὶ τοῦ τὰ ἔκγονα βελτίω τίκτειν ὑπὸ τοῦ ἐρρῶσθαι τὸ σῶμα· ἀφικομένη γὰρ ἐς ἀνδρὸς ὑδροφορεῖν οὐκ ὀκνήσει οὐδὲ ἀλεῖν διὰ τὸ ἠσκῆσθαι ἐκ νέας· εἰ δὲ καὶ νέῳ καὶ συγγυμναζομένῳ συζυγείη, βελτίω τὰ ἔκγονα ἀποδώσει, καὶ γὰρ εὐμήκη καὶ ἰσχυρὰ καὶ ἄνοσα. καὶ ἐγένετο ἡ Λακεδαίμων τοσαύτη κατὰ πόλεμον, ἐπειδὴ τὰ γαμικὰ αὐτοῖς ὧδε ἐπράττετο.