efutation of this assertion Darwin points to the decorative colours
of birds, which are used for display. And to the last objection, that
man alone has religion, that he alone has a belief in God, it is
answered "that numerous races have existed, and still exist, who have
no idea of one or more gods, and who have no words in their languages
to express such an idea."[100]

The result of the investigations recorded in this chapter is to show
that, great as the difference in mental powers between man and the
higher animals may be, it is undoubtedly only a difference "of degree
and not of kind."[101]

In the fourth chapter Darwin deals with the _moral sense_ or
_conscience_, which is the most important of all differences between
man and animals. It is a result of social instincts, which lead to
sympathy for other members of the same society, to non-egoistic
actions for the good of others. Darwin shows that social tendencies
are found among many animals, and that among these love and
kin-sympathy exist, and he gives examples of animals (especially dogs)
which may exhibit characters that we should call moral in man (e.g.
disinterested self-sacrifice for the sake of others). The early
ape-like progenitors of the human race were undoubtedly social. With
the increase of intelligence the moral sense develops farther; with
the acquisition of speech public opinion arises, and finally, moral
sense becomes habit. The rest of Darwin's detailed discussions on
moral philosophy may be passed over.

The fifth chapter may be very briefly summarised. In it Darwin shows
that the intellectual and moral faculties are perfected through
natural selection. He inquires how it can come about that a tribe at a
low level of evolution attains to a higher, although the best and
bravest among them often pay for their fidelity and courage with their
lives without leaving any descendants. In this case it is the
sentiment of glory, praise and blame, the admiration of others, which
bring about the increase of the better members of the tribe. Property,
fixed dwellings, and the association of families into a community are
also indispensable requirements for civilisation. In the longer second
section of the fifth chapter Darwin acts mainly as recorder. On the
basis of numerous investigations, especially those of Greg, Wallace,
and Galton, he inquires how far the influence of natural selection can
be demonstrated in regard to civilised nations. In the final