"Madness frequently discovers itself merely by unnecessary deviation from the usual modes of the world. My poor friend Smart shewed the disturbance of his mind, by falling upon his knees, and saying his prayers in the street, or in any unusual place. Now although, rationally speaking, it is greater madness not to pray at all, than to pray as Smart did, I am afraid there are so many who do not pray, that their understanding is not called into question."
From Boswell's Life of Johnson.