The entire region, continent and islands included, was one of diminutive size--not half so large as an ordinary Persian satrapy; it was well peopled, but its population could not have amounted to that of the Punjab or of Egypt, countries which Persia had overrun in a single campaign; its inhabitants were warlike, but they were comparatively poor, and the true sinews of war are money; moreover, they were divided amongst themselves, locally split up by the physical conformation of their country, and politically repugnant to anything like centralization or union.

A Persian king like Cambyses or Darius might be excused if, when his thoughts turned to Greece, he had a complacent feeling that no danger could threaten him from that quarter--that the little territory on his western border was a prey which he might seize at any time that it suited his convenience or seemed good to his caprice; so opening without any risk a new world to his ambition.

It required a knowledge that the causes of military success and political advance lie deeper than statistics can reach--that they have their roots in the moral nature of man, in the grandeur of his ideas and the energy of his character--in order to comprehend the fact, that the puny power upon her right flank was the enemy which Persia had most to fear, the foe who would gradually sap her strength, and finally deal her the blow that would lay her prostrate..