The Lumber Room: Mental Illness in the House of Medicine (second edition published in 2016) is a lively, literate examination of handbooks written to help doctors distinguish mental illness from physical illness. Evidence from the history of illness and of medicine is presented, including a glance at the evolution of the psychiatrists bible, the Diagnostic and Statistical Manual of Mental Disorders (DSM), and references to epilepsy, lycanthropy, syphilis, cancer, the Capgras delusion, malaria, Alzheimers disease, porphyria, multiple sclerosis, psychoanalysis, E.M. Forster, Samuel Johnson and Louis Pasteur. The author suggests that the editors of the next edition of the DSM consider renaming it the American Psychiatric Associations Diagnostic Manual, since the statistical part of the book was eliminated in 1980, and the editors declared the term mental disorder unsuitable in 1994.In the first two thirds of the essay, a critical look at these handbooks shows trends in psychiatry from the nineteenth century to today and touches on the many afflictions whose victims have been erroneously assigned to psychiatry instead of to other medical specialties. In the conclusion, the idea of a "God of the gaps" is introduced, that is, a deity whose bailiwick is everything that cant be explained by science: a poor argument for the existence of God because those gaps tend to get filled in. What these books show is a psychotherapist of the gaps, ready with psychological explanations and remedies until medicine advances and what was once, say, confusional psychosis or schizophrenia is found to be encephalitis or a brain tumor. The conclusion suggests that, with progress in medicine, difficult, unruly mental illnesses vanish and re-emerge as quantifiable, often curable physical illnesses."Lumber" is used here in the British sense meaning useless odds and ends. A house’s lumber room is where one stores those items that don’t belong anywhere else.