Freud's discovery of the dynamic unconscious is arguably his most important contribution to our understanding of the human mind. While others before him had realised that not all mental activity is conscious, it was Freud's aim to study in detail both the content and the alien mode of thinking of the unconscious mind. Dreams burst upon us, playing enigmatically upon our inner theatre, dense with obscure meaning. Freud showed the continuity between dreams, puzzling neurotic and psychotic symptoms, slips of the tongue and a multitude of errors which reveal the existence of the unconscious mind. The author explains that while we may have illusions of autonomy and conscious awareness of our motivations, psychoanalysis reveals that we are often "lived by" the unconscious which dwells within, largely hidden during daylight, but revealing its controlling influence within the dramas of sleep. Immensely creative yet powerfully destructive, the unconscious can be a source of guidance as well as subversion evoking both awe and dread.