Why Was Depression Once Blamed on Black Bile? The 2,500-Year-Old Theory Explained

Long before modern psychiatry existed, doctors had a very different explanation for depression. They blamed a bodily fluid called black bile. For roughly 2,500 years, this idea shaped how mental illness was understood and treated across the Western world. It influenced language, literature, and medicine alike. 

The Black Bile Theory was a core part of ancient humoral medicine, first proposed by Hippocrates around 400 BCE. It held that an excess of black bile, one of four essential bodily fluids, physically darkened the mind and caused melancholia. It was an ancient term closely resembling modern depression.

What Was the Black Bile Theory of Depression?

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image credit: Google Gemini AI

The theory traces back to the Greek physician Hippocrates around 400 BCE. According to humoral theory, the dominant medical framework from antiquity through the 19th century, the body contained four essential fluids, or humours:

• Blood
• Phlegm
• Yellow bile
• Black bile

When these fell out of balance, illness followed, both physical and mental. An excess of black bile specifically was believed to cause melancholia, the ancient term for what closely resembles modern depression, according to the Max Planck PhDnet.

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Where Does the Word "Melancholy" Actually Come From?

Directly from this theory. The word melancholia is transliterated from the ancient Greek melaina chole, literally meaning "black bile," according to the same Max Planck PhDnet source. Hippocrates characterised the condition specifically, describing symptoms that sound remarkably familiar today:

• Prolonged fear and despondency lasting a long time
• A persistent sense of sadness without an obvious cause
• Physical symptoms occurring alongside the psychological ones

This description comes from Hippocrates' own Aphorisms, according to Wikipedia's documented history of depression.

How Long Did the Black Bile Theory Actually Dominate Psychology?

Remarkably long. Humoralism remained the primary medical philosophy for treating mental illness until the middle of the 19th century, almost 2,500 years after Hippocrates first proposed it, according to FHE Health's overview of ancient mental health practices.

The theory wasn't confined to medicine either. Great writers, including Shakespeare, referenced humours when describing character, with Hamlet specifically thought to have too much black bile contributing to his melancholic worldview.

Did Anyone Challenge the Black Bile Theory Before It Ended?

Yes, centuries before it finally lost favour. Roman physician Asclepiades and philosopher Cicero, working between roughly 124 and 40 BC, rejected Hippocrates' humoral explanation entirely, arguing instead that melancholy arose from grief, fear, and rage rather than an excess of black bile, according to an open textbook on the history of psychological disorders.

Real theoretical progress toward today's understanding only arrived in the 19th century, led by figures like French physician Philippe Pinel, who pushed back against humoral treatments in favour of psychological approaches instead.

What We Got Wrong: A Humoral Era Reality Check

• Wrong cause: Depression stems from brain chemistry, genetics, and life circumstances, not excess bile
• Wrong organ: Blamed on the spleen and gallbladder, not the brain
• Wrong treatments: Bloodletting and purging caused harm and offered no real benefit
• Wrong universality: One vague explanation covered everything from sadness to arthritis

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Conclusion

The black bile theory of depression sounds absurd by modern standards, but it shaped psychology and medicine for roughly 2,500 years, longer than almost any other single medical theory in history. Its legacy still lives on in language, most obviously in the word "melancholy" itself, even though the underlying science has been completely replaced by our modern understanding of depression as a brain-based condition.