Amasis himself died just as the Persians were coming to attack Egypt, which Cyrus’ son Cambyses entirely conquered, and added to the Persian empire; but Cambyses shortly after lost his senses and died, and there was an unsettled time before a very able and spirited king named Darius obtained the crown, and married Cyrus’ daughter Atossa.  Among the prisoners made at Samos there was a physician named Democedes, who was taken to Susa, Darius’ capital.  He longed to get home, and tried not to show how good a doctor he was; but the king one day hurt his foot, and, when all the Persian doctors failed to cure him, he sent for Democedes, who still pretended to be no wiser, until torture was threatened, and he was forced to try his skill.  Darius recovered, made him great gifts, and sent him to attend his wives; but Democedes still pined for home, and managed to persuade Atossa to beg the king to give her Spartan and Athenian slaves, and to tell him some great undertaking was expected from him.  The doctor’s hope in this was that he should be sent as a spy to Greece, before the war, and should make his escape; but it was a bad way of showing love to his country.  Hippias was at Susa too, trying to stir up Darius to attack Athens, and restore him as a tributary king; and there was also Histiæus, a Greek, who had been tyrant of Miletus, and who longed to get home.  All the Ionian Greeks on the coast of Asia Minor hated the Persian rule, and Histiæus hoped that if they revolted he should be wanted there, so he sent a letter to his friend Aristagoras, at Miletus, in a most curious way.  He had the head of a trusty slave shaved, then, with a red-hot pin, wrote his advice to rise against the Persians, and, when the hair was grown again, sent the man as a present to Aristagoras, with orders to tell him to shave his head.