In the history of the relations between Greece and Persia this war is of doubtful importance;—doubtful, because it is not known how far it played a part in bringing about one of the most momentous resolutions that the people of Athens ever took. The great development of the silver coinage system about this time had made the demand for silver much greater than it had been previously. It was possibly owing to this cause that one of the lessees who held from the State silver mines at Laurion in South Attica, sought to increase the output by exploring deeper levels than had hitherto been worked. After sinking his shaft to a depth of 300 feet, he came upon lodes of ore infinitely richer than those at the higher levels, to which the workings had been hitherto confined. The date generally attributed to this discovery and its results is 484 B.C. The income which the State derived from the mines increased so greatly, that it became a question at Athens what had best be done with the money. This seems to have been about the time at which Themistocles, who was destined to play so great a part in the war of 480, came to the front in Athenian politics. He appears to have held high office some years before this time,[89] but his predominating influence in Athens coincides with the last five years of this decade. ◆H. vii. 144.◆ When it was proposed that the money thus accruing to the State should be divided among the citizens, he urged that a better use should be made of it in building 200 vessels for the navy. He carried the proposal. That is certain; but what is not certain is the nature of the motive which induced him to make it. Herodotus, whose account of Themistocles is drawn from sources hostile to this great man and to that phase of home politics of which he was in this and succeeding years the chief exponent,[90] attributes this proposal not to a wise foresight as to the plans of Persia, ◆H. vii. 144.◆ but to the immediate necessities of the war with Ægina. But Plutarch in his life of Themistocles has preserved a fuller record of his policy in the years preceding the great war of 480, a record which bears all the traces of reliability, and gives a wholly different colouring to the circumstances of the time. Themistocles’ policy with regard to naval matters was not suddenly sprung upon the world in the year 484 but dated from what must have been the very outset of his political career. Even before or immediately after the time of Marathon, he is advocating this policy in opposition to Miltiades.[91] ◆Plut. Them. 3.◆ Many regarded Marathon as the end of the war, but he looked upon it as the beginning only.