More than 50 years ago, a case study of amnesia with the patient Henry Molaison (H.M.) pioneered a new understanding of memory and the brain. This symposium will describe how memory was conceived before H.M. and how views changed since, summarize highlights of decades of research on H.M., describe new findings on brain-behavior correlations in H.M., present models of information processing in the hippocampus inspired by the findings on H.M., and describe insights about basic memory mechanisms, leading the way toward the treatment of memory loss in aging and age-related disease.