William worked on The Principles of Psychology throughout the 1880s, while teaching psychology and philosophy at Harvard University. He drew together various styles of science to create a unified whole and establish psychology as a valid discipline that connects many different areas—including philosophy, biology, and medicine—and helps us understand that the physical and mental are intertwined. He also created concepts—such as thoughts happening in a "stream of consciousness"—that have found their way into both the arts and popular conversation. This book is considered James' masterpiece, and it earned him the title of "the father of psychology."