An initial probability has been established by Mr. Darwin and Mr. Wallace that the reason or mind of man, as well as his body, has attained its present complete excellence through gradual development. No one denies that, between a man’s birth and his prime of life, time is required for the intellectual powers to unfold; but it demands an effort which few have as yet made to see in this progression of the individual mind a compendious history of the indefinitely slow process by which the human mind itself has been formed, passing upward, step by step, from simple vitality, dawning consciousness, the various grades of so-called instinct, to the full capacities of the most enlightened reason. The theory of development or evolution has excited immense opposition and distrust, because of its obvious application to the human body. Its application to the human mind, which, though less obvious at the first glance, almost inevitably follows, seems to have inspired Mr. Wallace himself with alarm. He winds up the admirable series of essays in which he supports the theory under discussion with one that earnestly propounds ‘the _limits_ of natural selection as applied to man.’ His arguments on this subject are drawn from physical science, though his mind is evidently, and even confessedly, swayed throughout by other than physical considerations. He represents, in fact, and endeavours to reconcile to his own scientific views, the weight of popular prejudice which has hitherto condemned those views with some vehemence of opposition.