Manual, a guide to the development and use of the Myers-Briggs type indicator

From the Introduction...

The purpose of the Myers-Briggs Type Indicator15 (MBTI®) is to make the theory of psychological types described by C. G. Jung (1921/1971) understandable and useful in people's lives. The essence of the theory is that much seemingly random variation in behavior is actually quite orderly and consistent, being due to basic differences in the way individuals prefer to use their perception and judgment.