Passage 10.21.5
τοὺς μὲν δὴ Ἕλληνας τὸ Ἀττικὸν ὑπερεβάλετο ἀρετῇ τὴν ἡμέραν ταύτην· αὐτῶν δὲ Ἀθηναίων Κυδίας μάλιστα ἐγένετο ἀγαθός, νέος τε ἡλικίαν καὶ τότε ἐς ἀγῶνα ἐλθὼν πολέμου πρῶτον. ἀποθανόντος δὲ ὑπὸ τῶν Γαλατῶν τὴν ἀσπίδα οἱ προσήκοντες ἀνέθεσαν τῷ Ἐλευθερίῳ Διί, καὶ ἦν τὸ ἐπίγραμμα· † ημαρλα δὴ ποθέουσα νέαν ἔτι Κυδίου ἥβην ἀσπὶς ἀριζήλου φωτός, ἄγαλμα Διί, ἇς διὰ δὴ πρώτας λαιὸν τότε πῆχυν ἔτεινεν, εὖτʼ ἐπὶ τὸν Γαλάταν ἤκμασε θοῦρος Ἄρης.
On this day the Athenians surpassed all the other Greeks in valor. Among the Athenians themselves, Cydias proved especially brave—a young man in age, then entering his first battle. After he was slain by the Gauls, his relatives dedicated his shield to Zeus Eleutherios, bearing the following inscription: Longing indeed for the youthful bloom of Cydias, the shield of that illustrious man, dedicated to Zeus— on my arm first he strapped me, when fierce Ares flared against the Galatian foe.