Explore the fascinating world of rock magnetism in this Bullard Lecture from the AGU Fall Meeting 2011. Delve into the history, key figures, and groundbreaking discoveries that have shaped the field. Learn about crucial concepts such as the Tillier Protocol, Araya Diagram, and paleo intensity determination. Discover the applications of rock magnetism in various contexts, including paleothermometry, volcanic rocks, and archaeological artifacts. Examine the Kapuskasing Structure and its significance in the field. Investigate intriguing mysteries surrounding Day plots, single-domain behavior, and wall moments. Gain insights into cutting-edge research using electron holographic images. This comprehensive one-hour lecture, presented by David J. Dunlop from the University of Toronto, offers a deep dive into both the successes and unresolved questions in rock magnetism.