Plato, Meno 83d

τοσησδί; ἢ οὔ; ἔμοιγε δοκεῖ οὕτω. καλῶς· τὸ γάρ σοι δοκοῦν τοῦτο ἀποκρίνου. καί μοι λέγε· οὐχ ἥδε μὲν δυοῖν ποδοῖν ἦν, ἡ δὲ τεττάρων; ναί. δεῖ ἄρα τὴν τοῦ ὀκτώποδος χωρίου γραμμὴν μείζω μὲν εἶναι τῆσδε τῆς δίποδος, ἐλάττω δὲ τῆς τετράποδος. δεῖ.

and half the size of this other? Yes. Will it not be made from a line longer than the one of these, and shorter than the other? I think so. Excellent: always answer just what you think. Now tell me, did we not draw this line two feet, and that four? Yes. Then the line on the side of the eight-foot figure should be more than this of two feet, and less than the other of four? It should.