scattered over a territory as large as France to form into a
score of separate herds, all marching towards a given spot, in
order to cross there a river. It is a feeling infinitely wider
than love or personal sympathy--an instinct that has been
slowly developed among animals and men in the course of an
extremely long evolution, and which has taught animals and men
alike the force they can borrow from the practice of mutual aid
and support, and the joys they can find in social life.

The importance of this distinction will be easily appreciated
by the student of animal psychology, and the more so by the
student of human ethics. Love, sympathy and self-sacrifice
certainly play an immense part in the progressive development of
our moral feelings. But it is not love and not even sympathy upon
which Society is based in mankind. It is the conscience--be it
only at the stage of an instinct--of human solidarity. It is
the unconscious recognition of the force that is borrowed by each
man from the practice of mutual aid; of the close dependency of
every one's happiness upon the happiness of all; and of the sense
of justice, or equity, which brings the individual to consider
the rights of every other individual as equal to his own. Upon
this broad and necessary foundation the still higher moral
feelings are developed. But this subject lies outside the scope
of the present work, and I shall only indicate here a lecture,
"Justice and Morality" which I delivered in reply to Huxley's
Ethics, and in which the subject has been treated at some length.

Consequently I thought that a book, written on Mutual Aid as
a Law of Nature and a factor of evolution, might fill an
important gap. When Huxley issued, in 1888, his