René Descartes' treatment of the relationship between causation and cognition is shaped by his dualism, viz., his view that mind and body are distinct substances with fundamentally different natures, thought and extension. This chapter explores the causal structure of Cartesian cognition in general, noting some of the metaphysical puzzles to which it gives rise. Sensory cognition is an especially complex form of cognition that causally links world, human body, and human mind. The causal structure of human cognition involves the complex causal interplay of world, human bodies, and human minds. The human mind’s involuntary cognitions have their causal origin in some body, at least when God is not playing tricks on us and causing them himself. The chapter aims to discover the psycho-physical and psycho-physiological laws that govern sensory cognition. An explicit aim of Descartes’ account of sensory processing is to replace the Aristotelian species theory.