"Many a man is mad in certain instances, and goes through life without having it perceived. For example, a madness has seized a person of supposing himself obliged literally to pray continually; had the madness turned the opposite way, and the person thought it a crime ever to pray, it might not improbably have continued unobserved."

Source: James Boswell, Samuel Johnson, Edmond Malone (1824). “The Life of Samuel Johnson, LL. D., Comprehending an Account of His Studies, and Numerous Works, in Chronological Order: A Series of His Epistolary Correspondence and Conversations with Many Eminent Persons; and Various Original Pieces of His Composition, Never Before Published; the Whole Exhibiting a View of Literature and Literary Men in Great Britain, for Near Half a Century During which He Flourished”, p.28