Stolen Faces (edition 1977)

More than once during these three months he asked himself, "Am I mad because I see what others do not, or are they mad that do these things that I see?"
Yet they (and there were many of them) did what seemed so astonishing and terrible to him with such quiet assurance that what they were doing was necessary and was important and useful work that it was hard to believe they were mad; nor could he, conscious of the clearness of his thoughts, believe he was mad; and all this kept him continually in a state of perplexity.


      -- Tolstoi, Resurrection, 1899