Plato, Laws 795a

σχεδὸν ἄνοια. ἔδειξεν δὲ ταῦτα ὁ τῶν Σκυθῶν νόμος, οὐκ ἐν ἀριστερᾷ μὲν τόξον ἀπάγων, ἐν δεξιᾷ δὲ οἰστὸν προσαγόμενος μόνον, ἀλλʼ ὁμοίως ἑκατέροις ἐπʼ ἀμφότερα χρώμενος· πάμπολλα δʼ ἕτερα τοιαῦτα παραδείγματα ἐν ἡνιοχείαις τέ ἐστι καὶ ἐν ἑτέροις, ἐν οἷσιν μαθεῖν δυνατὸν ὅτι παρὰ φύσιν κατασκευάζουσιν οἱ ἀριστερὰ δεξιῶν ἀσθενέστερα κατασκευάζοντες. ταῦτα δʼ, ὅπερ εἴπομεν, ἐν μὲν κερατίνοις πλήκτροις

This is shown by the Scythian custom not only of using the left hand to draw the bow and the right to fit the arrow to it, but also of using both hands alike for both actions. And there are countless other instances of a similar kind, in connection with driving horses and other occupations, which teach us that those who treat the left hand as weaker than the right are confuted by nature. But this, as we have said, matters little in the case of fiddle-bows of horn