image:Athanasius Kircher's Atlantis.gif Atlantis (in Greek, , "daughter of Atlas") is a legendary island first mentioned in Plato's dialogues Timaeus and Critias.

In Plato's account, Atlantis was a naval power lying "in front of the Pillars of Hercules" that conquered many parts of Western Europe and Africa 9,000 years before the time of Solon, or approximately 9600 BC. After a failed attempt to invade Athens, Atlantis sank into the ocean "in a single day and night of misfortune".

Scholars dispute whether and how much Plato's story or account was inspired by older traditions. Some scholars argue Plato drew upon memories of past events such as the Thera eruption or the Trojan War, while others insist that he took inspiration from contemporary events like the destruction of Helike in 373 BC or the failed Athenian invasion of Sicily in 415–413 BC.

The possible existence of a genuine Atlantis was actively discussed throughout classical antiquity, but it was usually rejected and occasionally parodied by later authors. As Alan Cameron states: "It is only in modern times that people have taken the Atlantis story seriously; no one did so in antiquity". While little known during the Middle Ages, the story of Atlantis was rediscovered by Humanists in the Early Modern period. Plato's description inspired the utopian works of several Renaissance writers, like Francis Bacon's "New Atlantis". Atlantis inspires today's literature, from science fiction to comic books to films, its name having become a byword for any and all supposed advanced prehistoric lost civilizations.

Plato's account

quote: For it is related in our records how once upon a time your State stayed the course of a mighty host, which, starting from a distant point in the Atlantic ocean, was insolently advancing to attack the whole of Europe, and Asia to boot. For the ocean there was at that time navigable; for in front of the mouth which you Greeks call, as you say, 'the pillars of Heracles,' there lay an island which was larger than Libya and Asia together; and it was possible for the travelers of that time to cross from it to the other islands, and from the islands to the whole of the continent over against them which encompasses that veritable ocean. For all that we have here, lying within the mouth of which we speak, is evidently a haven having a narrow entrance; but that yonder is a real ocean, and the land surrounding it may most rightly be called, in the fullest and truest sense, a continent. Now in this island of Atlantis there existed a confederation of kings, of great and marvelous power, which held sway over all the island, and over many other islands also and parts of the continent.

The four persons appearing in those two dialogues are the politicians Critias and Hermocrates as well as the philosophers Socrates and Timaeus of Locri, although only Critias speaks of Atlantis. While most likely all of these people actually lived, these dialogues, written as if recorded, may have been the invention of Plato. In his works Plato makes extensive use of the Socratic dialogues in order to discuss contrary positions within the context of a supposition.