They say there’s a fine line between genius and madness. Some of our foremost thinkers and artists have also suffered from mental illness and/or lived really tumultuous, troubling lives. A recent New Yorker cartoon featured a teenage girl blaming her parents for sinking her writing career by giving her a stable, happy childhood.

It turns out, we’ve been thinking this way for a long time.

In the mid-19th century, French doctor Jacques Joseph Moreau attributed genius and madness to an overexcitation of certain parts of the brain. Moreau was a follower of phrenology, a system developed by Franz Josef Gall (1758-1828), that attributed various human attributes to specific areas of the brain. These attributes were mapped on the brain and could be used to measured to determine certain things about a person. An overly emotional person probably had a larger emotion section of the brain, for example.

A phrenology map of the brain

Moreau took this idea a step farther and applied it to nervous disorders. He believed that nervous energy could become more concentrated and active in certain people, causing an overexcitation in one part of the brain that could either result in insanity or genius. A build of energy in the thinking part of the brain could lead to raving madness or it could lead to a great work of literature or a whole new philosophical system. Moreau believed that an exalted state of mind could allow genius to spring forth! But it didn’t work for everyone.

In his book Morbid Psychology, Moreau wrote that “the virtue and the vices [of overexcitation] can come from the same foyer, the virtue being the genius, the vice, idiocy.” That is, the genius was in constant danger of crossing the line because, according to Moreau, creative energy exhibits all of the reveries, trances, and exalted moments of inspiration that madness often has.

Moreau also did a lot of work with the effects of drugs on the central nervous system, writing a book called Hashish and Mental Alienation that has made him a hero of sorts for the marijuana crowd.

Moreau’s work, along with several other doctors and scientists, greatly influenced late 19th century interpretations of neuroses and its causes. It may also have helped popularize the notion of madness as an antecedent to the creative process.