πρὸς τὰς μεγίστας καὶ ἐλαχίστας ναῦς τὸ μέσον σκοπεῖν
From LSJ
ἐὰν ἃ τοῖς ἄλλοις ἐπιτιμῶμεν, αὐτοὶ μὴ δρῶμεν → avoid doing what you would blame others for doing
English > Greek (Woodhouse Quotes Reversed)
strike the mean between the largest also smallest number of ships given, to strike the average between the largest and smallest number of ships