Passage 9.3.3
Δαίδαλα οὖν ἄγουσιν οἱ Πλαταιεῖς ἑορτὴν διʼ ἔτους ἑβδόμου μέν, ὡς ἔφασκεν ὁ τῶν ἐπιχωρίων ἐξηγητής, ἀληθεῖ μέντοι λόγῳ διʼ ἐλάσσονος καὶ οὐ τοσούτου χρόνου· ἐθελήσαντες δὲ ἀπὸ Δαιδάλων ἐς Δαίδαλα ἕτερα ἀναριθμῆσαι τὸν μεταξὺ χρόνον ἐς τὸ ἀκριβέστατον οὐκ ἐγενόμεθα οἷοί τε. ἄγουσι δὲ οὕτω τὴν ἑορτήν.
The Plataeans celebrate the Daedala festival every seventh year, according to the account of the local guide; but in truth the interval is shorter and not as long as that. Despite our desire to reckon with complete precision the time interval from one Daedala festival to the next, we were not able to determine it exactly. They celebrate the festival in the following manner.