Hamlet by William Shakespeare (1601)

Who's there? The play begins with a question flung into the freezing dark, a sentry on the battlements of Elsinore challenging a shape he cannot name, and the whole tragedy turns out to be that question asked over and over, of a ghost, of a murderer, of the self. The ghost gives a prince one task: avenge a father poisoned by the uncle who now wears his crown and shares his mother's bed. Hamlet believes it, knows what is required, and cannot move. He thinks instead, more nakedly and more beautifully than anyone in the language had thought aloud before, until thought itself becomes the thing that stays his hand. When he stands alone and weighs being against not being, he is not really asking about death; he is asking whether a mind this awake can ever simply act. The answer takes five acts and leaves the stage strewn with the dead, and you feel the bodies coming long before they fall.