In like manner, if we find in caves or river-gravels, under circumstances implying enormous antiquity, and associated with remains of extinct animals, rude implements so exactly resembling those in use among existing savages, that if the collection in the Colonial Exhibition of stone celts and arrow-heads used by the Bushmen of South Africa were placed side by side with one from the British Museum of similar objects from Kent’s Cavern or the caves of the Dordogne, no one but an expert could distinguish between them, the conclusion is inevitable that Devonshire and Southern France were inhabited at some remote period by a race of men not more advanced than the Bushmen. Any theory of man’s origin and evolution which is to hold water must take account of this fact and square with it. And so of a vast variety of facts which have been reduced to law and become certainly known during the last half-century. A great deal of ground remains unexplored or only partially explored; but sufficient has been discovered to enable us to say that what we know we know thoroughly, and that certain leading facts and principles undoubtedly prevail throughout the knowable universe, including not only that which is known, but that which is as yet partially or wholly unknown. For instance, the law of gravity, the conservation of energy, the indestructibility of matter, and the law of evolution, or development from the simple to the complex. CHAPTER XI. RELIGIONS AND PHILOSOPHIES Religions, ‘working hypotheses’—Newman’s illative sense—Origins of religions—Ghosts and spirits—Fetishes—Nature-worship—Solar myths—Planets—Evolution of nature-worship—Polytheism, pantheism, and theism—Evolution of monotheism in the Old Testament—Evolution of morality—Natural law and miracle—Evidence for miracles—Insufficiency of evidence—Absence of intelligent design—Agnosticism—Origin of evil—Can only be explained by polarity—Optimism and pessimism—Jesus, the Christian Ormuzd—Christianity without miracles. Having thus, I may hope, given the reader some precise ideas of what are the boundaries and conditions of human knowledge, we may proceed to consider their application to the highest subjects, religions and philosophies.