This book presents a contextual study of the life and work of the Cambridge Platonist Ralph Cudworth (1617-1688). Focusing on the theological basis of Cudworth's ethical philosophy, this book unlocks the hitherto ignored political aspect to Cudworth's ethical philosophy. Through a detailed examination of Cudworth's published works - particularly his voluminous "True intellectual system of the Universe" -, his posthumously published writings, and his 'freewill' manuscripts Benjamin Carter argues that the ethical and political arguments in Cudworth's philosophy develop out of Cudworth's Trinitarian theology. Carter traces the link between Cudworth's trinitarianism and his ethical and political ideas by placing Cudworth's work in the turbulent religious and intellectual context of seventeenth-century England, and the University of Cambridge in particular.