Alison Gopnik in The Atlantic:
In 1734, in scotland, a 23-year-old was falling apart.
As a teenager, he’d thought he had glimpsed a new way of thinking and living, and ever since, he’d been trying to work it out and convey it to others in a great book. The effort was literally driving him mad. His heart raced and his stomach churned. He couldn’t concentrate. Most of all, he just couldn’t get himself to write his book. His doctors diagnosed vapors, weak spirits, and “the Disease of the Learned.” Today, with different terminology but no more insight, we would say he was suffering from anxiety and depression. The doctors told him not to read so much and prescribed antihysteric pills, horseback riding, and claret—the Prozac, yoga, and meditation of their day.
The young man’s name was David Hume. Somehow, during the next three years, he managed not only to recover but also, remarkably, to write his book. Even more remarkably, it turned out to be one of the greatest books in the history of philosophy: A Treatise of Human Nature.
In his Treatise, Hume rejected the traditional religious and philosophical accounts of human nature. Instead, he took Newton as a model and announced a new science of the mind, based on observation and experiment. That new science led him to radical new conclusions.