Owing to the great progress of ethnology during the century, we have learned a vast quantity of different kinds and practices of superstition, as they still survive in uncivilized races. When they are compared with each other and with the mythological notion of earlier ages, a manifold analogy is discovered, frequently a common origin, and eventually one simple source for them all. This is found in the "demand of causality in reason," in the search for an explanation of obscure phenomena by the discovery of a cause. That applies particularly to such phenomena as threaten us with danger and excite fear, like thunder and lightning, earthquakes, eclipses, etc. The demand for a causal explanation of such phenomena is found in uncivilized races of the lowest grade, transmitted from their primate ancestors by heredity. It is even found in many other vertebrates. When a dog barks at the full moon, or at a ringing bell, of which it sees the hammer moving, or at a flag that flutters in the breeze, it expresses not only fear, but also the mysterious impulse to learn the cause of the obscure phenomenon. The crude beginnings of religion among primitive races spring partly from this hereditary superstition of their primate ancestors, and partly from the worship of ancestors, from various emotional impulses, and from habits which have become traditional. The religious notions of modern civilized peoples, which they esteem so highly, profess to be on a much higher level than the "crude superstition" of the savage; we are told of the great advance which civilization has made in sweeping it aside. That is a great mistake. Impartial comparison and analysis show that they only differ in their special "form of faith" and the outer shell of their creed. In the clear light of reason the refined faith of the most liberal ecclesiastical religion--inasmuch as it contradicts the known and inviolable laws of nature--is no less irrational a superstition than the crude spirit-faith of primitive fetichism on which it looks down with proud disdain.