If materialism were the whole truth, it ought to explain the whole of heredity; instead of that it clashes with almost all the problems of life. Physical substance offers for analysis none but physical phenomena: attraction, repulsion, heat, electricity, magnetism, vital movement; the anatomical constitution of the highest--the nerve--tissue, presents only the slightest differences in the animal series, if these differences are compared with the enormous distinctions in the qualities it expresses. Differences of form, visible to the microscope, are at times important, we shall be told, and those that affect the atomic activity and groupings[71] are perhaps even more important. That is true, especially in whatever concerns man. Intelligence cannot always be explained by the complexity of the brain--though this complexity is the condition of faculty, as a rule--insects such as ants, bees, and spiders, whose brains are nothing but simple nerve ganglia, display prodigies of foresight, architectural ability and social qualities; whilst along with these dwarfs of the animal kingdom, we see giants that manifest only a rudimentary mind, in spite of their large, convoluted brains. Among the higher animals, there is not one that could imitate the beaver--which, all the same, is far from being at the head of the animal series--in building for itself a house in a river and storing provisions therein. There is a vast gulf, in the zoological series, before and after these insects, as there is before and after the beaver; whilst an even wider gulf separates the highest specimens of the animal world from man himself. Nor do the weight and volume of the brain afford any better explanation of the difference in intellect than does its structural complexity. The weight relations between the brain and the body of different animals have been estimated as follows by Debierre (_La Moelle et l' Encephale_):-- Rabbit 1 of brain for 140 of body. Cat 1 " 156 " Fox 1 " 205 " Dog 1 " 351 " Horse 1 " 800 " If matter were the only condition _sine qua non_ of intelligence, we should have to admit that the rabbit was more intelligent than the cat, the fox, the dog, and even than the horse. In the same work the following figures express the average size of the brain in different races of men. Pariahs of India 1332 cubic centimetres. Australians 1338 " Polynesians 1500 " Ancient Egyptians 1500 " Merovingians 1537 " Modern Parisians 1559 "