Plural Temporality traces out a dynamic historical relationship between the texts of Spinoza and Althusser. It interrogates Spinoza’s thought through Althusser’s and vice versa, with the intention of opening new horizons for the question of materialism. From the fragmentary intuitions Althusser produced about Spinoza throughout his life, Morfino builds a new and comprehensive interpretation of Spinoza’s philosophy. In the later sections of the book, this interpretation is put to work to help to clarify some of the more problematic aspects of the late Althusser’s philosophy, thereby offering new concepts for a materialist position in philosophy and the development of Marxist theory.