I. THALES.-For several centuries prior to the great Persian invasions of Greece, perhaps the very greatest and wealthiest city of the Greek world was Miletus. Situate about the centre of the Ionian coasts of Asia Minor, with four magnificent harbours and a strongly defensible position, it gathered to itself much of the great overland trade, which has flowed for thousands of years eastward and westward between India and the Mediterranean; while by its great fleets it created a new world of its own along the Black Sea coast.