B.C.), a disciple of the more practical Ionian school, and a pupil or companion of Thales, conceived an earth of the form of a cylinder. He is said to have introduced into Greece the gnomon, a primitive instrument for determining time and latitude, and to have made a map. The first actual record of a Greek or Miletan map, however, occurs half a century after his time, when in 499 B.C. Aristagoras, tyrant of Miletus, asked aid of Cleomenes of Sparta against Persia, and showed him a map, engraved on bronze, of the route of his proposed expedition. Anaximenes, of Anaximander’s school, gave the earth an oblong rectangular form. The physical division of land into continents, though obvious, presupposes the existence of a certain measure of geographical theory. Still more obvious as a primitive division would be a division simply between “my land” and “yours.” But there was a clear necessity at a very early period for names to distinguish, generally, the lands which lay on one side and the other of the Ægean-Mediterranean waters. It may well be that the names of Europe and Asia did not possess precisely this application in their original forms. Their derivation has been assigned to an Asiatic source; they signify on this view the lands respectively of darkness or sunset and of sunrise or light--that is to say, the lands towards west and towards east. The earliest known Greek reference to Europe, moreover, does not indicate on the face of it a distinction from Asia, though it does indicate a distinction from lands separated from it partly or wholly by water. The Homeric hymn to Apollo, which may be dated in the eighth or seventh century B.C., refers to dwellers in the rich Peloponnese and in Europe and in the sea-girt islands--albeit in place of “Europe” some scholars would read a word signifying simply “mainland.” The name of Europe, if admitted here, is taken to mean no more than northern Greece, and would thus lend some colour to an early tradition that it was derived from a Macedonian city called Europus. However this may be, it is easy to conceive that the name of Europe, being at no time given to a territory with defined frontiers, was capable of an elastic application, which would be gradually extended, or (as is more probable under primitive conditions of geographical knowledge) would remain so vague as to permit of no clear definition.