We act in accordance with our self-image. This self-image—which,
in turn, governs our every act—is conditioned in varying degree by three
factors: heritage, education, and self-education.
The part that is inherited is the most immutable. The biological
endowment of the individual—the form and capacity of his nervous
system, his bone structure, muscles, tissue, glands, skin, senses—are all
determined by his physical heritage long before he has any established
identity. His self-image develops from his actions and reactions in the
normal course of experience....