τούτου δὲ συμβαίνοντος ἀναγκαῖον γίγνεσθαι πάροδον καὶ τροπὰς τῶν ἐνδεδεμένων ἄστρων → but if this were so, there would have to be passings and turnings of the fixed stars
secret, imperceptible: P. and V. λαθραῖος.
treacherous: P. ἐπίβουλος, V. μηχανορράφος.
unsound: P. and V. ὕπουλος, σαθρός.