The historical sketch and criticism here attempted had its proximate origin in two consecutive years' work with a senior class of sociology at Lancashire College. In 1896-97, essays were prescribed on topics suggested by Mr. Benjamin Kidd's Social Evolution; while the seniors of 1897-98 attended lectures covering rather more ground. The material thus collected has been again revised and again considerably added to. The literature of the subject is always growing. Some books of consequence, old or new, must have been overlooked. Still, it is hoped that the subject itself has well-defined limits. The appeal to biology, outlined by Comte, newly defined and emphasised by Darwinism, has now been stated in the most extreme form logically possible. Mr. Kidd's book holds that significant position.

In studying the questions raised, the author has found himself, though with certain grave reserves, more and more thrown back upon philosophical principles learned at Glasgow, above twenty years ago, from the present Master of Balliol College.