"The Interpretation of Dreams" by Sigmund Freud is a book published in 1899 that introduces his groundbreaking theory of the unconscious through dream analysis. Freud argues that dreams are forms of wish fulfillment, shaped by unconscious forces and mental censorship. He distinguishes between a dream's manifest content—what we remember—and its latent content—the hidden meaning beneath. Through processes of condensation, displacement, and symbolism, dreams become puzzles that, when interpreted, reveal the "royal road" to understanding the unconscious mind.