This early work attempts to describe and categorize mental illnesses; first published in 1812, it predates the establishment of psychology and psychiatry as formal fields of medicine.

The author notes a variety of correlations in those who suffer from mental illness; their lifestyles and professions, and whether they are related to those with similar ailments. He concisely observes how manias - then a general term for madness - manifest. The symptoms of various kinds of illness, and their effects on memory, behavior, physical condition and personality, are listed. Most of the terminology and suggestions for treatment are outdated and obsolete, but carry historic value in showing how the earliest treatments were administered to those incapacitated by diseases of the mind.

Benjamin Rush was a Founding Father who held the role of Surgeon General in the United States. He was a bold and pioneering researcher and practitioner of medicine, with his attempts to understand mental maladies applauded during and after his death. At a time when the mentally stricken were confined to asylums, often in degrading and inhumane conditions, Rush's researches and learning represented a significant evolution in the field. Considered a symbol of the medical Enlightenment, in the modern day Rush is termed the 'father of American psychiatry'.