There is nothing to lead us to suppose that primitive man had felt the existence of a principle higher than nature. There is much to indicate that what we mean by religious feeling was not known to him; but the aspect of the question undergoes a change if by religious sentiment we understand belief in invisible spirits, for this belief was universal. This is natural; as soon as certain faculties of the imagination awoke in man, such as astonishment, curiosity, he would seek to understand all that passed around him; his first idea would be that all the phenomena in nature would proceed from the presence inherent in them of a power compelling to action in the same way as man feels himself obliged to act. This belief in the course of age would easily tend towards fetishism, then to polytheism and finally to monotheism; it would simultaneously inculcate many strange superstitions, of which some produced terrible effects, such as the sacrifice of human lives to a powerful being eager for human blood, since savages readily attribute to these superior powers the desire for vengeance as well as all the other evil passions they themselves possess. Amongst civilised peoples the conception of an all-knowing, an all-seeing God, exercises a powerful influence on morality; man learns little by little, no longer to regard the praise or blame of society as his sole guide; this external guidance is replaced by personal inward convictions which come from his reason and which is conscience. Religious devotion is a very complex human sentiment; it is composed of love, submission, gratitude, hope, and perhaps of other elements; no creature is in a position to experience so complicated an emotion whose intellectual faculties have not attained a level of medium development. Yet something approaching this may be seen in the depth of affection manifested by a dog for his master, which is a combination of complete submission, of fear, dependence, and perhaps also of other qualities. Learned writers have for some time agreed in looking upon language as the barrier separating man from animals; all books on logic state the fact. But this special characteristic of the human race attracted Darwin’s attention in a very small degree. “Man, however, at first, uses, in common with the lower animals, inarticulate cries to express his meaning, aided by gestures and the movements of the muscles of the face.”[12] “Certain animals,” he says, “do not lack the physical conditions necessary for articulate language, since there is not a letter in the alphabet that a parrot cannot pronounce.” Darwin goes even beyond this. “It is not the mere power of articulation that distinguishes man from other animals, but it is his large power of connecting definite sounds with definite ideas.”[12]