In this book, Martin Lenz provides the first reconstruction of intersubjective accounts of the mind in early modern philosophy by providing a historical and rational reconstruction of three central, but different, early modern accounts of the influence that minds exert on one another: Spinoza's metaphysical model, Locke's linguistic model, and Hume's medical model. Showing for each model of mental interaction (1) why it was developed, (2) how it construes mind-mind relations, and (3) what view of the mind it suggests, this book aims at uncovering a crucial part of the unwritten history of intersubjectivity in the philosophy of mind.