Passage 8.36.5
Μεγαλοπολίταις δὲ διὰ τῶν ἐπὶ τὸ ἕλος ὀνομαζομένων πυλῶν, διὰ τούτων ὁδεύουσιν ἐς Μαίναλον παρὰ τὸν ποταμὸν τὸν Ἑλισσόντα ἔστι τῆς ὁδοῦ ἐν ἀριστερᾷ Ἀγαθοῦ θεοῦ ναός· εἰ δὲ ἀγαθῶν οἱ θεοὶ δοτῆρές εἰσιν ἀνθρώποις, Ζεὺς δὲ ὕπατος θεῶν ἐστιν, ἑπόμενος ἄν τις τῷ λόγῳ τὴν ἐπίκλησιν ταύτην Διὸς τεκμαίροιτο εἶναι. προελθόντι δὲ οὐ πολὺ ἔστι μὲν γῆς χῶμα Ἀριστοδήμου τάφος, ὃν οὐδὲ τυραννοῦντα ἀφείλοντο μὴ ἐπονομάσαι Χρηστόν, ἔστι δὲ Ἀθηνᾶς ἱερὸν ἐπίκλησιν Μαχανίτιδος, ὅτι βουλευμάτων ἐστὶν ἡ θεὸς παντοίων καὶ ἐπιτεχνημάτων εὑρέτις.
For the Megalopolitans, as one goes through the gate known as the Gate toward the Marsh, by this road heading toward Maenalus alongside the river Helisson, there is on the left a temple of the Good God. Now if the gods indeed bestow good things upon people, and Zeus is supreme among the gods, one might reasonably conclude from this argument that this epithet refers to Zeus. A little further along is an earthen mound, the tomb of Aristodemus, whom they did not refrain from calling 'the Good', even though he was a tyrant. There is also a sanctuary of Athena surnamed Machanitis ("the Inventive"), because the goddess is considered the originator of all sorts of strategies and ingenious devices.