Eviatar Zerubavel explores how the seven-day week, one of the most fundamental structures organizing human experience, became so deeply embedded in consciousness that we rarely question its arbitrary origins. Unlike months and years, which correspond to lunar and solar cycles, the week has no basis in natural phenomena. Zerubavel traces its emergence in ancient Mesopotamia, its adoption and transformation by Jewish, Christian, and Islamic traditions, and its eventual global spread. He examines how the week structures social life, from work and rest patterns to market days and religious observances, creating rhythms that feel natural despite being entirely cultural inventions. The book explores failed attempts to reform the week, including the French Revolutionary calendar's ten-day decade and the Soviet Union's experiments with five and six-day weeks, showing how deeply the seven-day pattern resists modification. Zerubavel analyzes the cultural meanings attached to different days, from Monday's melancholy to Friday's anticipation, revealing how temporal structures shape emotional experience. As a sociologist, he uses the week to illuminate larger questions about how social conventions become second nature, constraining behavior while remaining invisible. The book challenges readers to notice the artificial structures that organize their lives and consider how differently time might be experienced under alternative arrangements.