The Four Classical Temperaments: From Hippocratic Humors to Modern Personality Neuroscience

1. Ancient Roots: Humoral Medicine and Early Typology

Around 400 BCE, Greek physician Hippocrates proposed that physiological health depends upon the equilibrium of four bodily fluids (humors): blood, yellow bile, black bile, and phlegm. Later in the 2nd century CE, the Roman physician Galen systematized these humors into physiological and psychological constitutions, coining the term "temperamentum" (proper mixture).

While medical science eventually replaced humoral pathology with modern cellular microbiology, Galen’s behavioral archetypes persisted for over two millennia because they accurately captured four observable patterns of human reactivity.

2. The Eysenckian Revolution: Two Modern Biological Axes

In the mid-20th century, British psychologist Hans Eysenck demonstrated that the four classical temperaments map precisely onto a two-dimensional coordinate plane defined by two fundamental neurobiological systems:

The Horizontal Axis: Extraversion vs. Introversion

Rooted in the baseline arousal of the Ascending Reticular Activating System (ARAS) in the brainstem. Extraverts have lower baseline cortical arousal and seek stimulation; Introverts have higher baseline arousal and seek tranquility.

The Vertical Axis: Emotional Stability vs. Neuroticism

Rooted in the reactivity of the limbic system, sympathetic autonomic nervous system, and visceral brain.

3. Comprehensive Profiles of the Four Archetypes

4. Inter-Temperament Communication and Conflict Dynamics

Relational misunderstandings frequently erupt when different temperaments fail to translate each other’s primary psychological currencies:

5. Practical Alchemy: Balancing Your Primary and Secondary Blend

Rarely does an individual exhibit a pure single temperament. Most people operate as a dual blend, such as Sanguine-Choleric (an energetic crusader) or Melancholic-Phlegmatic (a quiet scholar).