He did not, however, make his distinctive feature as distinct as he should have done. Sometimes he said one thing, and sometimes the directly opposite. Sometimes, for example, the conditions of existence “included natural selection” or the fact that the best adapted to their surroundings live longest and leave most offspring; {156a} sometimes “the principle of natural selection” “fully embraced” “the expression of conditions of existence.” {156b} It would not be easy to find more unsatisfactory writing than this is, nor any more clearly indicating a mind ill at ease with itself. Sometimes “ants work _by inherited instincts_ and inherited tools;” {157a} sometimes, again, it is surprising that the case of ants working by inherited instincts has not been brought as a demonstrative argument “against the well-known doctrine of _inherited habit_, as advanced by Lamarck.” {157b} Sometimes the winglessness of beetles inhabiting ocean islands is “mainly due to natural selection,” {157c} and though we might be tempted to ascribe the rudimentary condition of the wing to disuse, we are on no account to do so—though disuse was probably to some extent “combined with” natural selection; at other times “it is probable that disuse has been the main means of rendering the wings of beetles living on small exposed islands” rudimentary. {157d} We may remark in passing that if disuse, as Mr. Darwin admits on this occasion, is the main agent in rendering an organ rudimentary, use should have been the main agent in rendering it the opposite of rudimentary—that is to say, in bringing about its development. The ostensible _raison d’être_, however, of the “Origin of Species” is to maintain that this is not the case.