Tracing the development of horror entertainment since the late 18th century, this study argues that scientific discovery, technological progress, and knowledge in general have played an unparalleled role in influencing the evolution of horror. Throughout its many subgenres and formats, horror records humanity’s uneasy relationship with its own ability to reason, understand, and learn. The text first outlines a loose framework defining several distinct periods in horror development, then explores each period sequentially by looking at the scientific and cultural background of the period, its expression in horror literature, and its expression in horror visual and performing arts.