A full account of this expedition, and of the various adventures which the party met with on their voyage, is given in our history of Darius. It may be proper to say here, however, that the physician fully succeeded in his plans of making his escape. He pretended, at first, to be unwilling to go, and he made only the most temporary arrangements in respect to the conduct of his affairs while he should be gone, in order to deceive the king in regard to his intentions of not returning. The king, on his part, resorted to some stratagems to ascertain whether the physician was sincere in his professions, but he did not succeed in detecting the artifice, and so the party went away. The physician never returned. Atossa had four sons. Xerxes was the eldest of them. He was not, however, the eldest of the sons of Darius, as there were other sons, the children of another wife, whom Darius had married before he ascended the throne. The oldest of these children was named Artobazanes. Artobazanes seems to have been a prince of an amiable and virtuous character, and not particularly ambitious and aspiring in his disposition, although, as he was the eldest son of his father, he claimed to be his heir. Atossa did not admit the validity of this claim, but maintained that the oldest of _her_ children was entitled to the inheritance. It became necessary to decide this question before Darius's death; for Darius, in the prosecution of a war in which he was engaged, formed the design of accompanying his army on an expedition into Greece, and, before doing this, he was bound, according to the laws and usages of the Persian realm, to regulate the succession. There immediately arose an earnest dispute between the friends and partisans of Artobazanes and Xerxes, each side urging very eagerly the claims of its own candidate. The mother and the friends of Artobazanes maintained that he was the oldest son, and, consequently, the heir. Atossa, on the other hand, contended that Xerxes was the grandson of Cyrus, and that he derived from that circumstance the highest possible hereditary rights to the Persian throne. This was in some respects true, for Cyrus had been the founder of the empire and the legitimate monarch, while Darius had no hereditary claims. He was originally a noble, of high rank, indeed, but not of the royal line; and he had been designated as Cyrus's successor in a time of revolution, because there was, at that time, no prince of the royal family who could take the inheritance. Those, therefore, who were disposed to insist on the claims of a legitimate hereditary succession, might very plausibly claim that Darius's government had been a regency rather than a reign; that Xerxes, being the oldest son of Atossa, Cyrus's daughter, was the true representative of the royal line; and that, although it might not be expedient to disturb the possession of Darius during his lifetime, yet that, at his death, Xerxes was unquestionably entitled to the throne.