Note 76 — Chapter I · THE MILESIAN SCHOOL
Reading edition
The oldest version of this story is given in Diog. i. 27, ὁ δὲ Ἱερώνυμος καὶ ἐκμετρῆσαί φησιν αὐτὸν τὰς πυραμίδας, ἐκ τῆς σκιᾶς παρατηρήσαντα ὅτε ἡμῖν ἰσομεγέθης ἐστίν. Cf. Pliny, H. Nat. xxxvi. 82, mensuram altitudinis earum deprehendere invenit Thales Milesius umbram metiendo qua hora par esse corpori solet. (Hieronymos of Rhodes was contemporary with Eudemos.) This need imply no more than the simple reflexion that the shadows of all objects will probably be equal to the objects at the same hour. Plutarch (Conv. sept. sap. 147 a) gives a more elaborate method, τὴν βακτηρίαν στήσας ἐπὶ τῷ πέρατι τῆς σκιᾶς ἣν ἡ πυραμὶς ἐποίει, γενομένων τῇ ἐπαφῇ τῆς ἀκτῖνος δυοῖν τριγώνων, ἔδειξας ὃν ἡ σκιὰ πρὸς τὴν σκιὰν λόγον εἶχε, τὴν πυραμίδα πρὸς τὴν βακτηρίαν ἔχουσαν. This, as Dr. Gow points out, is only another calculation of seqt, and may very well have been the method of Thales.