The ideas connected with perjury have this further value for the history of ethics, that they contributed much to the growth of international morality. It is {149} often supposed that the earliest morality is merely tribal or clannish, and that in respect of the alien it is nonexistent; but this account of morality is false wherever perjury is found to be a sin. For one great occasion for oath-taking is a treaty or a contract with an alien power. And Homer is our witness that it was considered an immoral act for either Achaeans or Trojans to break their mutual oath. And this early idea of international morality inspires the Tel-El-Amarna correspondence and the Hittite treaty with Rameses. International morality also includes the duty of hospitality, and the pre-Homeric world had developed this moral sense strongly, and no doubt through the aid of religion; the stranger who puts himself into communion with Hestia, the holy hearth, or with Zeus Xenios, has a moral right to protection, and the abduction of Helen was regarded as a sin on the part of Paris against Zeus the god of the guest-right. I have not yet been able to find a cult-concept in Babylonian religion parallel to that of Zeus Xenios, or any reference to hospitality as a sacred duty; yet we know that this was and is as highly regarded by some Semitic races as it ever was by the Hellenic. We may suspect, however, that as Babylonian society was in many respects very modern and complex, the religious sanction of hospitality had decayed.