What happens in our minds when we unintentionally perceive fantastic stories or see patterns and shapes? How do such hallucinations differ from real experiences or dream states? Are they connected to past experiences or our secret desires? In his new book, New York neurologist Oliver Sacks explores the topic of hallucinations. He begins with Charles Bonnet, a Swiss physician who was the first to systematically study the phenomenon in the 18th century. He then connects this historical perspective to the present, sharing numerous case studies from his own patients. The imaging techniques used in brain research today provide entirely new insights into the courses and causes of hallucinations. Sacks also examines the hallucinatory effects of certain drugs and substances, such as mescaline, cocaine, or hashish. He describes the relationship between hallucinations and artistic production through notable figures like Charles Baudelaire, Frédéric Chopin, and Aldous Huxley. As in all his books, Oliver Sacks offers fascinating insights into the world of the human brain, combining empathetic storytelling, scientific scholarship, and a keen eye for the curious.