This is the story of an exciting and hugely successful 25-year collaboration between two scientists. David Hubel and Torsten Wiesel set out to learn how the brain deals with the signals it receives from the eyes, and opened up a new area of brain research that led to their receiving the Nobel Prize in 1981. The book contains their major papers from 1959 to 1981, each with comments telling how and why the authors went about the study, how the work was received, and what has happened since. It begins with short autobiographies of both men, and describes the state of the field when they started. It is intended not only for neurobiologists, but for anyone interested in how the brain works - biologists, psychologists, philosophers, physicists, historians of science, and students at all levels.