On instincts, habits, feelings and human nature: different habits and feelings grow out of different instinct. “Their totality is the nature of man.”
According to the authors, “known history shows little alteration in the conduct of mankind.” That is, we behave pretty much the same as our ancestors four thousand years ago. Even though the means and instruments have changed, the motives and ends remain the same throughout human history.
There are always these six pair of instincts: to act or rest; to acquire or give; to fight or flight; to associate or privacy; to mate or reject; to offer or resent parental care. You find these instincts among human beings, regardless of culture and social class. As long as you are human beings, you exhibit these instincts.
Evolution in man has been social rather than biological. “It has proceeded not by heritable variations in the species, but mostly by economic, political, intellectual, and moral innovation transmitted to individuals and generations by imitation, custom, or education.”