incalculably great differences in the social structure, in the amount of knowledge, in the character of the ethical, religious, and philosophical beliefs, and in the relations between the individuals of which the society is constructed; but between the individuals at the two periods we may find hardly any definable difference whatever. For anything we can say, we should be able, if we could move people about in time as well as in space, to exchange a thousand infants of the nineteenth century A.D., for a thousand of the nineteenth century B.C., and nobody would be able to detect the difference which would result. Hence it follows, in my opinion, that the evolutionary process with which moralists and political philosophers have practically to deal, is what I have called the social, and not the individual process. We inherit thoughts as we inherit wealth; we inherit customs and laws and forms of worship, and indeed our whole mental furniture; we can add enormously to our inheritance, and can transmit the augmented fund to our descendants. But the other process of inheritance, to which the word "heredity" is taken to apply, is not, immediately at least, cumulative. We inherit the old faculties, bodily and mental, unaltered, or with infinitesimal alterations, though we live in a different environment, and are ourselves as much altered as our environment. The modern social organism is built up, if I may say so, of cells almost identical in their properties with those of the old organism, although the mode of combination gives entirely new properties to the whole, and brings out new actions and reactions among the constituent cells themselves.