Passage 2.12.3
ἡ δὲ Φλιασία τῆς Σικυωνίων ἐστὶν ὅμορος· καὶ Τιτάνης μὲν τεσσαράκοντα σταδίους ἀπέχει μάλιστα ἡ πόλις, ἐκ Σικυῶνος δὲ ἐς αὐτὴν ὁδός ἐστιν εὐθεῖα. καὶ ὅτι μὲν Ἀρκάσι Φλιάσιοι προσήκουσιν οὐδέν, δηλοῖ τὰ ἐς τὸν Ἀρκάδων κατάλογον τῆς Ὁμήρου ποιήσεως, ὅτι οὐκ εἰσὶν Ἀρκάσι καὶ οὗτοι συγκατειλεγμένοι· ὡς δὲ Ἀργεῖοί τε ἦσαν ἐξ ἀρχῆς καὶ ὕστερον Δωριεῖς γεγόνασιν Ἡρακλειδῶν κατελθόντων ἐς Πελοπόννησον, φανεῖται προϊόντι ὁμοῦ τῷ λόγῳ. διάφορα δὲ ἐς τοὺς Φλιασίους τὰ πολλὰ εἰδὼς εἰρημένα, τοῖς μάλιστα αὐτῶν ὡμολογημένοις χρήσομαι.
The territory of Phlious borders on that of the Sicyonians. The city of Titane is situated about forty stades away, and the road from Sicyon to Titane is a direct one. That the Phliasians bear no kinship to the Arcadians is clearly shown by the Catalogue of Arcadians in Homer's poetry, in which they are not included with the Arcadians. That originally they were Argives, and afterwards became Dorians when the Heracleidae descended into the Peloponnese, will become clear as my account proceeds. Since I have found many differing statements concerning the Phliasians, I shall chiefly rely on those facts upon which they themselves most agree.