biological foundation of instinct, and
secondly an educability of the conceptual intelligence which
refashions and rearranges the data afforded by previous inheritance
and acquisition. It is in relation to this second and higher order of
educability that the cerebrum of man shows so large an increase of
mass and a yet larger increase of effective surface through its rich
convolutions. It is through educability of this order that the human
child is brought intellectually and affectively into touch with the
ideal constructions by means of which man has endeavoured, with more
or less success, to reach an interpretation of nature, and to guide
the course of the further evolution of his race--ideal constructions
which form part of man's environment.

It formed no part of Darwin's purpose to consider, save in broad
outline, the methods, or to discuss in any fulness of detail the
results of the process by which a differentiation of the mental
faculties of man from those of the lower animals has been brought
about--a differentiation the existence of which he again and again
acknowledges. His purpose was rather to show that, notwithstanding
this differentiation, there is basal community in kind. This must be
remembered in considering his treatment of the biological foundations
on which man's systems of ethics are built. He definitely stated that
he approached the subject "exclusively from the side of natural
history."[192] His general conclusion is that the moral sense is
fundamentally identical with the social instincts, which have been
developed for the good of the community; and he suggests that the
concept which thus enables us to interpret the biological ground-plan
of morals also enables us to frame a rational ideal of the moral end.
"As the social instincts," he says,[193] "both of man and the lower
animals have no doubt been developed by nearly the same steps, it
would be advisable, if found practicable, to use the same definition
in both cases, and to take as the standard of morality, the general
good or welfare of the community, rather than the general happiness."
But the kind of community for the good of which the social instincts
of animals and primitive men were biologically developed may be
different from that which is the product of civilisation, as Darwin no
doubt realised. Darwin's contention was that conscience is a social
instinct and has been evolved because it is useful to the tribe in the
struggle for exi