History of the Peloponnesian War

The same winter the Athenians, with greater forces than they had before sent out with Laches and Eurymedon, resolved to go again into Sicily, and, if they could, wholly to subdue it, being for the most part ignorant both of the greatness of the island, and of the multitude of people, as well Greeks as barbarians, that inhabited the same, and that they undertook a war not much less than the war against the Peloponnesians.

For the compass of Sicily is little less than eight days' sail for a ship; and though so great, is yet divided with no more than twenty furlongs, sea measure, from the continent.