A.beginning, originating, “λόγος ἀρχηγὸς κακῶν” E.Hipp.881; primary, leading, chief, “Τροίας ἀ. τιμάς” Id.Tr.196 (lyr.); “δύο φλέβες ἀ.” Arist.PA666b25.
II. as Subst., founder, of a tutelary hero, S.OC60; as fem., ancestral heroine, B.8.51; “τοῦ γένους” Isoc.3.28, cf. D.S.5.56; “τῆς πόλεως θεὸς ἀ. τίς ἐστιν” Pl.Ti. 21e; founder of a family, Arist.EN1162a4.
2. prince, chief, “Δία ἀ. θεῶν” B.5.179, cf. A.Ag.259; chief captain, leader, “Ἑλλάνων” Simon. 138; “Βεβρύκων” Theoc.22.110; “ἀ. ἱερέων” CIG6798 (Dijon), cf. 2882 (Milet.).
3. first cause, originator, “κοπίδων” Heraclit.81; “πράγματος” X.HG3.3.4, cf. Din.3.7, Isoc.12.101; “συγχύσεως” SIG684.8 (Dyme, ii B.C.); “φόνου” POxy.1241 iii 35; “σωτηρίας” Ep.Hebr.2.10; “Θαλῆς ὁ τῆς τοιαύτης ἀ. φιλοσοφίας” Arist.Metaph.983b20; “τῆς τέχνης” Sosip.1.14; “τὸ ἀ.” the originating power, Pl.Cra.401d, cf. Sph.243d; primary, fundamental, “ἀρχηγὸν ἡ φωνή” Phld.Po.2.19.