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.

The Life of Samuel Johnson, LL. D., Comprehending an Account of His Studies, and Numerous Works, in Chronological Order (ed. 1824)