ABSTRACT
We have already taken note in passing of some ways in which people are alike. The distribution curve does not divide them into separate classes. Individuals differ in degree rather than in kind. Some are more intelligent than others, but they all have some intelligence. They all have the verbal, numerical, spatial, and other abilities in some degree, they all make some use of past experience in handling a novel situa tion, they all have some ability to grasp relationships. Even in personality traits they do not show the absolute differences which are often assumed. No one is entirely good or entirely bad. Everyone, when tested, reveals some introversion and some extraversion. Everyone is affected by the physiological and social factors in personality. And the interaction of heredity and environment is an important general law. There are many principles of psychology which apply to the activities of all individuals.
