The Man Who Was Thursday: A Nightmare is a novel by G. K. Chesterton, first published in 1908. The book is sometimes referred to as a metaphysical thriller.In Edwardian era London, Gabriel Syme is recruited at Scotland Yard to a secret anti-anarchist police corps. Lucian Gregory, an anarchistic poet, lives in the suburb of Saffron Park. Syme meets him at a party and they debate the meaning of poetry. Gregory argues revolt is the basis of poetry. Syme demurs, insisting the essence of poetry is not revolution, but rather law. He antagonizes Gregory by asserting the most poetical of human creations is the timetable for the London Underground. He suggests Gregory isn't really serious about his anarchism. This so irritates Gregory that he takes Syme to an underground anarchist meeting place, revealing his public endorsement of anarchy is a ruse to make him seem harmless, when in fact he is an influential member of the local chapter of the European anarchist council.