This conception of life, especially of religious life, was therefore very popular from the beginning of our era. It was manifestly prior both to Christianity and to Mithraism. It developed in the military monarchies of the Asiatic Diadochi. Here the soldier was no longer a citizen defending his country, but in most instances a volunteer bound by a sacred vow to the person of his king. In the martial states that fought for the heritage of the Achemenides this personal devotion dominated or displaced all national feeling. We know the oaths taken by those subjects to their deified kings.[7] They agreed to defend and uphold them even at the cost of their own lives, and always to have the same friends and the same enemies as they; they dedicated to them not only their actions and words, but their very thoughts. Their duty was a complete abandonment of their personality in favor of those monarchs who were held the equals of the gods. The sacred _militia_ of the mysteries was nothing but this civic {xxi} morality viewed from the religious standpoint. It confounded loyalty with piety. As we see, the researches into the doctrines or practices common to Christianity and the Oriental mysteries lead almost always beyond the limits of the Roman empire into the Hellenistic Orient. The religious conceptions which imposed themselves on Latin Europe under the Caesars[8] were developed there, and it is there we must look for the key to enigmas still unsolved. It is true that at present nothing is more obscure than the history of the religions that arose in Asia when Greek culture came in contact with barbarian theology. It is rarely possible to formulate satisfactory conclusions with any degree of certainty, and before further discoveries are made we shall frequently be compelled to weigh contrasting probabilities. We must frequently throw out the sounding line into the shifting sea of possibility in order to find secure anchorage. But at any rate we perceive with sufficient distinctness the direction in which the investigations must be pursued. It is our belief that the main point to be cleared up is the composite religion of those Jewish or Jewish-pagan communities, the worshipers of Hypsistos, the Sabbatists, the Sabaziasts and others in which the new creed took root during the apostolic age. In those communities the Mosaic law had become adapted to the sacred usages of the Gentiles even before the beginning of our era, and monotheism had made concessions to idolatry. Many beliefs of the ancient Orient, as for instance the ideas of Persian dualism regarding the infernal world, arrived in Europe by two roads, the more or less orthodox Judaism of the communities of {xxii} the dispersion in which the gospel was accepted immediately, and the pagan mysteries imported from Syria or Asia Minor. Certain similarities that surprised and shocked the apologists will cease to look strange as soon as we reach the distant sources of the channels that reunited at Rome.