The term "matter" and its cognates ("material," "materialist," "materialistic," and the like) have played active parts in philosophical debate throughout intellectual history. Natural philosophers have studied material objects and contrasted them with such immaterial agencies as energy and fields of force; metaphysicians and mathematical philosophers have distinguished the material or tangible aspects of things from their formal or intangible aspects, their physical properties from their geometrical ones. Again, the terms "matter" and "material" have played a humble part not only in science but also in moral philosophy and even theology. Matter has thus been placed in opposition to life and mind, soul and spirit, and a preoccupation with worldly pleasures and bodily comforts, as opposed to the "higher" pleasures of the mind, has been condemned as "materialistic" and unworthy of spiritual beings. In thinking about matter, accordingly, the question of how far—if at all—these various distinctions...