Some years elapsed before these arrangements were matured, and when at last the time seemed to have arrived for carrying his plans into effect, he deemed it necessary, before he commenced his march, to settle the succession of his kingdom; for he had several sons, who might each claim the throne, and involve the empire in disastrous civil wars in attempting to enforce their claims, in case he should never return. The historians say that there was a law of Persia forbidding the sovereign to leave the realm without previously fixing upon a successor. It is difficult to see, however, by what power or authority such a law could have been enacted, or to believe that monarchs like Darius would recognize an abstract obligation to law of any kind, in respect to their own political action. There is a species of law regulating the ordinary dealings between man and man, that springs up in all communities, whether savage or civilized, from custom, and from the action of judicial tribunals, which the most despotic and absolute sovereigns feel themselves bound, so far as relates to the private affairs of their subjects, to respect and uphold; but, in regard to their own personal and governmental acts and measures, they very seldom know any other authority than the impulses of their own sovereign will. Darius had several sons, among whom there were two who claimed the right to succeed their father on the throne. One was the oldest son of a wife whom Darius had married before he became king. His name was Artobazanes. The other was the son of Atossa, the daughter of Cyrus, whom Darius had married _after_ his accession to the throne. His name was Xerxes. Artobazanes claimed that he was entitled to be his father's heir, since he was his oldest son. Xerxes, on the other hand, maintained that, at the period of the birth of Artobazanes, Darius was not a king. He was then in a private station, and sons could properly inherit only what their fathers possessed at the time when they were born. He himself, on the other hand, was the oldest son which his father had had, _being a king_, and he was, consequently, the true inheritor of the kingdom. Besides, being the son of Atossa, he was the grandson of Cyrus, and the hereditary rights, therefore, of that great founder of the empire had descended to him. Darius decided the question in favor of Xerxes, and then made arrangements for commencing his march, with a mind full of the elation and pride which were awakened by the grandeur of his position and the magnificence of his schemes. These schemes, however, he did not live to execute. He suddenly fell sick and died, just as he was ready to set out upon his expedition, and Xerxes, his son, reigned in his stead.