Plato, Meno 83b

γένωνται; ναί. ἀναγραψώμεθα δὴ ἀπʼ αὐτῆς ἴσας τέτταρας. ἄλλο τι ἢ τουτὶ ἂν εἴη ὃ φῂς τὸ ὀκτώπουν εἶναι; πάνυ γε. οὐκοῦν ἐν αὐτῷ ἐστιν ταυτὶ τέτταρα, ὧν ἕκαστον ἴσον τούτῳ ἐστὶν τῷ τετράποδι; ναί. πόσον οὖν γίγνεται; οὐ τετράκις τοσοῦτον; πῶς δʼ οὔ; διπλάσιον οὖν ἐστιν τὸ τετράκις τοσοῦτον; οὐ μὰ Δία. ἀλλὰ ποσαπλάσιον; τετραπλάσιον. ἀπὸ τῆς διπλασίας

Then let us describe the square, drawing four equal lines of that length. This will be what you say is the eight-foot figure, will it not? Certainly. And here, contained in it, have we not four squares, each of which is equal to this space of four feet? Yes. Then how large is the whole? Four times that space, is it not? It must be. And is four times equal to double? No, to be sure. But how much is it? Fourfold.