Plato, Meno 83c

ἄρα, ὦ παῖ, οὐ διπλάσιον ἀλλὰ τετραπλάσιον γίγνεται χωρίον. ἀληθῆ λέγεις. τεττάρων γὰρ τετράκις ἐστὶν ἑκκαίδεκα. οὐχί; ναί. ὀκτώπουν δʼ ἀπὸ ποίας γραμμῆς; οὐχὶ ἀπὸ μὲν ταύτης τετραπλάσιον; φημί. τετράπουν δὲ ἀπὸ τῆς ἡμισέας ταυτησὶ τουτί; ναί. εἶεν· τὸ δὲ ὀκτώπουν οὐ τοῦδε μὲν διπλάσιόν ἐστιν, τούτου δὲ ἥμισυ; ναί. οὐκ ἀπὸ μὲν μείζονος ἔσται ἢ τοσαύτης γραμμῆς, ἀπὸ ἐλάττονος δὲ ἢ

Thus, from the double-sized line, boy, we get a space, not of double, but of fourfold size. That is true. And if it is four times four it is sixteen, is it not? Yes. What line will give us a space of eight feet? This one gives us a fourfold space, does it not? It does. And a space of four feet is made from this line of half the length? Yes. Very well; and is not a space of eight feet double the size of this one,