ζῆν οὐκ ἄξιος, ὅτῳ μηδὲ εἷς ἐστι χρηστὸς φίλος → life is not worth living if you do not have at least one friend
εἰδότως, ἐγνωσμένως, εἰδήμων, ἔμπειρος, εἰδημονικός