In Freudian dream analysis, content is both the manifest and latent content in a dream, that is, the dream itself as it is remembered, and the hidden meaning of the dream. Dreams embody the involuntary occurrences within the mind throughout various stages of sleep. Throughout the early part of the twentieth century, psychologist Sigmund Freud made incredible advances in the study and analysis of dreams. Freud's The Interpretation of Dreams (1899) used an evolutionary biological perspective to infer that these nightly visions are a product of one's individual psyche. As the "royal road to the unconscious", dreams allow for accessibility to parts of the mind that are inaccessible through conscious thought. According to his psychoanalytic theory, dreams—like most psychological experiences—can