Toward a four-factor theory of temperament and/or personality

This article makes a case for a four-factor theory of temperament/personality, tracing its origin to Hippocrates, who first postulated a four-factor theory of temperament in 400 B.C. Historical developments are discussed as they relate to the postulation of a four-factor mode, continuing from Galen in the 2nd century A.D. to the present day. Theoretical formulations are discussed along with considerations of applications in the field of personality assessment.