The Man Who Was Thursday: A Nightmare is a novel by G. K. Chesterton, first published in 1908. The book has been referred to as a metaphysical thriller. Although it deals with anarchists, the novel is not an exploration or rebuttal of anarchist thought; Chesterton's ad hoc construction of "Philosophical Anarchism" is distinguished from ordinary anarchism and is referred to several times not so much as a rebellion against government but as a rebellion against God.