Source: Merenda, P. F. (1987). "Toward a Four-Factor Theory of Temperament and/or Personality". Journal of Personality Assessment. 51: 367–374.
A 100 page image based book, with rhythmical pacing, contains a collection of visuals that describe 4 temperaments. The temperaments were named for the four bodily fluids of ancient medical theory: sanguine, melancholic, choleric, and phlegmatic, with specific personality traits attributed to each. These four categories were developed into a medical theory by Greek physician Hippocrates (460–370 BC).*
Source: Merenda, P. F. (1987). "Toward a Four-Factor Theory of Temperament and/or Personality". Journal of Personality Assessment. 51: 367–374.