The concept of four ‘humours’ – yellow bile, black bile, phlegm, and blood – was first introduced in ancient Greece. This theory has had a lasting impact on how we view personality types for thousands of years. The famous story of Petruchio and his wife Katherine from Shakespeare’s “The Taming of the Shrew” is a prime example. Modern audiences may be less aware that Katherine’s intolerance was attributed to an excess of yellow bile, leading to a stubborn and hot-headed disposition.
This theory, known as humoral theory, was widely accepted until the Enlightenment period. It dictated health advice based on one’s humour type, including diet, lifestyle, and even where they should live. Although the biological assertions have been discredited, some of its influence can still be seen in modern psychological models.
Greek philosopher Empedocles is credited with developing the theory, while Hippocrates refined it. Later, German-British personality theorist Hans Eysenck built upon this concept and created two main personality dimensions: neuroticism and extraversion. This approach led to four “types” that sound eerily similar to the ancient taxonomy.
Eysenck’s work was groundbreaking, but his ideas have been influenced by criticisms of racism. Today, the Big Five personality model dominates, adding openness, conscientiousness, and agreeableness to neuroticism and extraversion. Researchers have found correlations between these dimensions, leading some to conceptualize two higher-order factors: “plasticity” and “stability.”
While there is debate about whether these two higher order factors really exist, the concept of four personality types remains a fascinating area of study. DeYoung’s work hints that our personalities can be summarized in different ways, but not through clear-cut categories. Labelling people with specific types still faces challenges due to arbitrary cut-offs between categories.
The human desire for classification and understanding has been around since recorded history. Our fascination with personality types will continue, as it provides a powerful tool for organizing information and interacting with the world.
Source: https://www.bbc.com/future/article/20250915-the-ancient-origins-of-todays-personality-types