Euclid of Megara
Euclid of Megara (435-365 BC) was a Greek philosopher and a pupil of Socrates. Although he wrote six dialogues, none have survived. Our principal source is Diogenes Laërtius who quoted excerpts from him.
Josiah Priest refers to Euclid as a believer in the reality of Atlantis in his 1835 book American Antiquities [1143.82/3]. Apparently, Euclid met with Anacharsis the Scythian philosopher and their discussions turned to the ‘convulsions of the globe’ including the separation of Sicily from Italy and the destruction of Atlantis.
Similarly, in the Atlantic, “there existed, according to ancient traditions, an island as large as Africa, which, with all its wretched inhabitants was swallowed up by an earthquake.”
Beyond the isthmus, of which I have just spoken, said Euclid, according to ancient traditions, an island as large as Africa, which, with all its wretched inhabitants, was swallowed up by an earthquake.
Priest then refers to Euclid again [p.83] claiming that “here, then, is another witness, besides Solon, who lived 300 years before the time of Euclid, who testifies to the past existence of the island of Atalantis.”
Furthermore, according to Euclid, it was the Black Sea that broke into the Aegean Sea, rather than the other way round. Since Anacharsis came from the northern coast of the Black Sea we can reasonably assume that he had local knowledge to back up this suggestion!