"While my book attempts to reflect the full range of scholarly debate, I have also attempted to make it useful to anyone interested in Whitehead. To this end, I have introduced the Whiteheadian terms one by one, explaining each in the light of my interpretation, and I have used examples wherever possible. I try to show that Whitehead intended his philosophy have a place in our lives by reshaping our common conceptions, and that he did not intend it to be relegated to purely abstract or esoteric application." — F. Bradford Wallack The twentieth century has seen the greatest innovations in philosophical cosmology since Newton and Descartes, and Alfred North Whitehead was the first and greatest of the philosophers to work out these innovations in systematic ways. In a book that will be controversial in the philosophical community, F. Bradford Wallack argues that interpretations widely accepted by Whiteheadians need revaluation because these interpretations are based on materialist and substantialist assumptions that Whitehead sought to replace. Specifically, she proposes a thorough revision of accepted interpretations of Whitehead's concept of the actual entity. Wallack then elucidates Whitehead's ideas in order of their increasing dependence upon other basic Whiteheadian terms to complete the study of Whiteheadian time and to clarify its purpose within the cosmology of Process and Reality. Whitehead's philosophy then emerges as more intelligible and cohesive than is generally believed.