Although the descent of man from animal ancestors was directly implied in the "Origin of Species," Darwin hesitated at the time of its publication to declare his views fully, believing that he would only thus augment and concentrate the prejudice with which his theory would be met. He had for many years held the views he afterwards expressed; but it was not until he had by his other works raised up a strong body of scientific opinion in favour of his great generalisation, that he fully presented his views on man to the public. The "Descent of Man" was studied as a special case of the application of his general principles, a test all the more severe because several classes of argument were necessarily cut off, such as the nature of the affinities which connect together whole groups of organisms, their geographical distribution, and their geological succession. But adopting the high antiquity of man as demonstrated, he considered in detail the evidence as to man's descent from some pre-existing form, the manner of his development, and the value of the differences between the so-called races of man. No originality is claimed for the theory or for the facts advanced; but it may safely be affirmed that the master's acuteness, his moderation, his candour, and his desire to state facts which tell against him, are as conspicuous in the "Descent of Man" as in any of his works. The "Descent of Man," which was published in 1871 in two volumes, with numerous illustrations, began, after a short introduction, with a suggestive series of questions, which to the evolutionist suffice to decide the question as to man's origin. As the answers to these questions are obvious, Darwin first concentrated his inquiry upon two points on which disputes must necessarily occur, namely, the traces which man shows, in his bodily structure, of descent from some lower form, and the mental powers of man as compared with those of lower animals. The facts of our bodily structure are inexplicable on any other view than our community of descent with the quadrumana, unless structure is but a snare to delude our reason. It is only our natural prejudice, says Darwin, and that arrogance which made our fathers declare that they were descended from demigods, which leads us to demur to this conclusion.