History animates dynamical systems at different timescales.* Brains, people (with their embodied minds and their more or less m indful bodies), small groups, and institutions are all open to the past, both to specific past events and to general past trends and practices, without in general being overwhelmed by it. Coordinating change at many different rates and at many different levels of organization, these interacting and history-dependent open systems exhibit and contribute to a range of phenomena related to remembering. But how do they incorporate and acton the basis of their pasts? By what mechanisms, and through what media do traces shape the behavior of these systems?