There was, indeed, one defect in the theory of the new system. From time immemorial the polity of the empire had been based on the family relation. The sovereign reigned in virtue of his lineage, and the hereditary nobles owed their high positions and administrative competence equally to descent. To discredit the title of the nobles was to disturb the foundation of the Throne itself, and to affirm that want of virtue constituted a valid reason for depriving the scions of the gods of their inherited functions, was to declare constructively that the descendant of Amaterasu also held his title by right of personal worthiness. That was the Chinese theory. Their history shows plainly that they recognized the right of men like Tang or Wu to overturn tyrants like Chieh of the Hsia dynasty, and Chou of the Yen dynasty. The two Japanese Emperors, Kotoku and Tenchi (668-671), seem to have partially endorsed a cognate principle. But nothing could be at greater variance with the cardinal tenet of the Japanese polity, which holds that "the King can do no wrong" and that the Imperial line must remain unbroken to all eternity. ENVOYS TO CHINA The importance attached to intercourse with China during the reign of Kotoku was illustrated by the dimensions of the embassies sent to the Tang Court and by the quality of the envoys. Two embassies were sent in 653, one consisting of 121 persons and the other of 120.* The former included seventeen student-priests, and among them was the eldest son of Kamatari himself. Another embassy was despatched in 654, and the records show incidently that the sea route was taken, for after a voyage lasting some months and therefore presumably of a coasting character, the envoys landed at Laichou in Shantung. They finally reached Changan, the Tang capital, and were most hospitably received by the Emperor Kao-sung. The hardships of the journey are attested by the fact that three of the student-priests died at sea. One remained in China for thirty-six years, and Joye, Kamatari's son, did not return to Japan for twelve years. *The ship carrying the embassy was wrecked off the south coast of Japan, and out of 120 persons only five escaped.