Mr. Darwin has since introduced a paragraph concerning Lamarck into the "historical sketch," already more than once referred to in these pages. In this he summarises the theory which I am about to lay before the reader, by saying that Lamarck "upheld the doctrine that all species, including man, are descended from other species." If Lamarck had been alive he would probably have preferred to see Mr. Darwin write that he upheld "the doctrine of descent with modification as the explanation of all differentiations of structure and instinct." Mr. Darwin continues, that Lamarck "seems" to have been chiefly led to his conclusion on the gradual change of species, "by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain groups, and by the analogy of domestic productions." Lamarck would probably have said that though he did indeed turn--as Mr. Darwin has done, and as Buffon and Dr. Darwin had done before him--to animals and plants under domestication, in illustration and support of the theory of descent with modification; and that though he did also insist, as so many other writers have done, on the arbitrary and artificial nature of the distinction between species and varieties, he was mainly led to agree with Buffon and Dr. Darwin by a broad survey of the animal kingdom, with the details also of which few naturalists have ever been better acquainted. "Great," says Mr. Darwin, "is the power of steady misrepresentation,"--and greatly indeed has the just fame of Lamarck been eclipsed in consequence; "but," as Mr. Darwin finely continues, "the history of science shows that fortunately this power does not long endure."[198] That Lamarck anticipated it, was prepared to face it, and even felt that things were thus, after all, as they should be, will appear from the shrewd and pleasant passage which is to be found near the close of his preface:-- "So great is the power of preconceived opinion, especially when any personal interest is enlisted on the same side as itself, that though it is hard to deduce new truths from the study of nature, it is still harder to get them recognized by other people. "These difficulties, however, are on the whole more beneficial than hurtful to the cause of science; for it is through them that a number of eccentric, though perhaps plausible speculations, perish in their infancy, and are never again heard of. Sometimes, indeed, valuable ideas are thus lost; but it is better that a truth, when once caught sight of, should have to struggle for a long time without meeting the attention it deserves, than that every outcome of a heated imagination should be readily received.