Alfred Adler

The science of human nature should not be approached with too much presumption and pride. On the contrary, its practitioners are notable for exercising a certain modesty. The understanding of human nature is an enormous problem, whose solution has been the goal of our culture since time immemorial. It is not a science that should be pursued by a few specialists only. Its proper objective must be the understanding of human nature by every human being.

Alfred Adler, Understanding Human Nature, page 16