A Dissertation of Freret (Memoires de l'Academie des Inscriptions, tom. x. p. 357-377) affords a happy union of philosophy and erudition. The phenomenon in the time of Ogyges was preserved by Varro (Apud Augustin. de Civitate Dei, xxi. 8.), who quotes Castor, Dion of Naples, and Adastrus of Cyzicus - nobiles mathematici. The two subsequent periods are preserved by the Greek mythologists and the spurious books of Sibylline verses.