But it was, perhaps, fortunate for the liberties of Greece that Themistocles, instead of Aristides, was left in full power at Athens. "The peculiar faculty of his mind," says THIRLWALL, "which Thucydides contemplated with admiration, was the quickness with which it seized every object that came in its way, perceived the course of action required by new situations and sudden junctures, and penetrated into remote consequences. Such were the abilities which were most needed at this period for the service of Athens." Soon after the battle of Marathon a war had broken out between Athens and Ægina, which still continued, and which gave Themistocles an opportunity to exercise his powers of ready invention and prompt execution. Ægina was one of the wealthiest of the Grecian islands, and possessed the most powerful navy in all Greece. Themistocles soon saw that to successfully cope with this formidable rival, as well as rise to a higher rank among the Grecian states, Athens must become a great maritime power. He therefore obtained the consent of the Athenians to devote a large surplus then in the public treasury, but which belonged to individual citizens, to the building of a hundred galleys; and, by this sacrifice of individual emolument to the general good, the Athenian navy was increased to two hundred ships. But the foresight of Themistocles extended still farther, and it was no less his design, in making Athens a first-class maritime power, to protect her against Persia, which, as he well knew, was preparing for another and still more formidable attack on Greece. * * * * * III. THE SECOND' PERSIAN INVASION. For three years subsequent to the battle of Marathon Darius made great preparations for a second invasion of Greece, intending to lead his forces in person; but death put an end to his plans. Xerxes, his son and successor, was urged by many advisers to carry out his father's intentions. His uncle Artaba'nus alone endeavored to divert him from the enterprise; but Xerxes, having spent four years in collecting a large fleet and a vast body of troops from all quarters of his extensive dominions, set out from Sardis with great ostentation, in the spring of the year 480, to avenge the disgrace of Marathon. HERODOTUS relates that, on reaching Aby'dos, on the Hellespont, Xerxes reviewed his vast host, and wept when he thought of the shortness of human life, and considered that of all his immense host not one man would be alive when a hundred years had passed away. The historian's account is as follows: Xerxes at Abydos.