We need a spur to keep us up to our best effort, so the instinct of

emulation emerges
We need a spur to keep us up to our best effort, so the instinct of
emulation emerges. We must defend ourselves, so the instinct of
pugnacity is born. We need to be cautious, hence the instinct of fear.
We need to be investigative, hence the instinct of curiosity. Much
self-directed activity is necessary for our development, hence the play
instinct. It is best that we should come to know and serve others, so
the instincts of sociability and sympathy arise. We need to select a
mate and care for offspring, hence the instinct of love for the other
sex, and the parental instinct. This is far from a complete list of our
instincts, and I have not tried to follow the order of their
development, but I have given enough to show the origin of many of our
life"s most important activities.