And preëminently the same is it with religion. Religion has been a great part of the life of man, and the historian of morals must be a diligent student of the religious systems of the world, but mainly because religion has been in general such a potent agency in the moral education of mankind. For it is the ethical factor in the great world religions which constitutes their universal and permanent element. “It is the function of religion to kindle moral enthusiasm in society at large.”[4] “Christianity has no other function or value than as an aid to morality.”[5] All the great religions of the world--Buddhism, Confucianism, Zoroastrianism, Judaism (reckoning historic Judaism as beginning with the great prophets of the ninth and eighth centuries B.C.), Christianity, and Islam--began as moral reforms.[6] In short, in the words of Wellhausen, “Morality is that for the sake of which all other things exist; it is the alone essential thing in the world.”[7] The really constructive and regulative forces in history are in truth moral ideas and convictions. And there is vast significance in this--that the ethical motive, never absent and always active, is constantly becoming more and more dominant in the processes of the historical evolution. As the ages pass there enters into history--we shall see this to be so later--an ever larger ethical element. Conscience becomes ever more and more involved in the personal, national, and international affairs of the world. [Sidenote: The history of morals in the main a record of the expansion of the circle covered by the moral feelings] Moral progress consists not so much in changes in the quality or intensity of the moral emotions, although these gain in diversity, purity, and refinement as time passes, as in the successive enlargements of the circle of persons embraced by the moral feelings.[8] “It is not the sense of duty to a neighbor, but the practical answer to the question, Who is my neighbor? that has varied.”[9] As we shall see when we come to examine the morality of primitive man, the moral feelings embrace at first only kinsmen, that is, the members of one’s own family, clan, or social group. All others are outside the moral pale. But gradually this circle grows larger and embraces in successive expansions the tribe, the city, the nation, and lastly humanity.