THIS is a very remarkable book; and one which must have a good effect in preparing students of sociology for the inevitable changes which are rapidly coming upon us. It is thoroughly scientific in its methods, inasmuch as it is based upon the theory of evolution; yet it is altogether original in its treatment of the subject, and gives us a theory of social progress which is in many respects very different from that generally accepted by evolutionists. This theory appears on the whole to be a sound one, although the author has fallen into certain errors which will be pointed out. These, however, do not materially affect the general theory. Social Evolution. By Benjamin Kidd. (London: Macmillan and Co., 1894.)