Ancient Greek
Paragraph 90
Theon Smyrnaeus, De utilitate mathematicae 90
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διαφέρει δὲ ἀναλογίας μεσότης, ἐπειδὴ εἰ μέν τι ἀναλογία, τοῦτο καὶ μεσότης, εἰ δέ τι μεσότης, οὐκ εὐ- θὺς ἀναλογία. ἐγχωρεῖ γάρ τι κατὰ τάξιν μέσον ὅν μὴ ἔχειν ἀναλόγως πρὸς τὰ ἄκρα· ὡς τὰ δύο μέσα ἐστὶ τῇ τάξει 〈τοῦ ἑνὸς καὶ〉 τῶν γʹ, καὶ τοῦ ἑνὸς καὶ 〈τῶν ιʹ〉 τὰ γʹ καὶ τὰ δʹ καὶ τὰ εʹ· ἀπὸ γὰρ τοῦ ἑνὸς οὐχ οἷόν τε ἐλθεῖν ἐπὶ τὰ ι΄ μὴ πρότερον ἐλθόντα ἐπὶ τὰ β΄ καὶ τὰ γ΄ καὶ τὰ δ. ἀλλʼ οὐδὲν τούτων ἀναλόγως ἔχει πρὸς τὰ ἄκρα. τὸ γὰρ ἓν οὐκ ἐν τούτῳ ἐστὶ τῷ λόγῳ πρὸς τὰ β, ἐν ᾧ τὰ β΄ πρὸς τὰ γ΄· ὁμοίως καὶ ἐπὶ τῶν β΄ καὶ γ΄ καὶ δ΄. τὰ δὲ ἐν τῷ αὐτῷ λόγῳ ὄντα καὶ μέσα ἂν εἴη, οἷον ἔν β΄ δ΄. ἀναλογία τε γάρ ἐστιν ἡ τοῦ δι- πλασίου, καὶ τά β΄ μέσα τοῦ ἑνὸς καὶ τῶν δ΄.