The speaker is talking about______.

Fantasy is a tough sell in the twentieth century. The world has been tully discovered and fully mapped. Popular media has effectively minimized the legend and the fantastic rumor, though to make up for this it has generated falsities not as lavish but just as interesting. Satellites have mapped and studied the earth, leaving only a space frontier that is as yet unreachable. But standing out is a charming fantasy the modern world has yet to verify or condemn: the lost continent of Atlantis. The father of the modern world’s perception of Atlantis is Plato. The Greek philosopher spoke in his works Timaeus and Critias of a continent in the Atlantic ocean larger than Africa and Asia Minor combined which rivaled Athens as the most advanced in the world. According to the legend surrounding Plato’s dialogues, the island of Atlantis was violently thrown into the sea by the forces of nature, and its few survivors managed to swim ashore and relate their story. There the legend was passed by word of mouth until an Egyptian priest related the story to Solon, a character in Timaeus. The priest admired the achievements of prehistoric Athenians, because when the rulers of Atlantis threatened to invade all of Europe and Asia, the Athenians, on behalf of all Greeks, defeated the Atlanteans to avoid enslavement.