[Footnote 10: For a thorough discussion of the importance of this
instinct, see Trotter's _Instincts of the Herd in Peace and War_.]

=Acquisition.= Another fundamental disposition in both animals and
men is the instinct for possession, the instinct whose function it is
to provide for future needs. Squirrels and birds lay up nuts for the
winter; the dog hides his bone where only he can find it. Children
love to have things for their "very own," and almost invariably go
through the hoarding stage in which stamps or samples or bits of
string are hoarded for the sake of possession, quite apart from their
usefulness or value. Much of the training of children consists in
learning what is "mine" and what is "thine," and respect for the
property of others can develop only out of a sense of one's own
property rights.

=Construction.= There is an innate satisfaction in making
something,--from a doll-dress to a poem,--and this satisfaction rests
on the impulse to construct, to fashion something with our own hands
or our own brain. The emotion accompanying this instinct is too
indefinite to have a name but it is nevertheless a real one and plays
a large part in the sense of power which results from the satisfaction
of good work well done. Later it will be seen how closely related is
this impulse to the creative instinct of reproduction and how useful
it can be in drawing off the surplus energy of that much denied
instinct.

=Pugnacity and Anger.= What is it that makes us angry? A little
thought will convince us that the thing which arouses our fury is not
the sight of any special object, but the blocking of any one of the
other instincts. Watch any animal at bay when its chance for flight