This chapter deals with different early modern routes leading from causation to cognition. Explaining cognition in terms of representation required a detailed analysis of the nature of ideas. The idea that certain causal processes are required for there to be cognition is a very natural one, certainly in the case of perceptual cognition. In fact, this idea is so natural that it seems hard to deny. Descartes mockingly remarked that forms, real qualities, and other scholastic entities are “nothing but chimeras.” Most anti-Aristotelians rejected the relation between the internal capacity and the external form and replaced it with the relation of representation. On their view, the intellect reacts to input coming from the body by forming ideas that represent external things, and they insisted that the representing ideas are really distinct from the represented things. A cognitive requirement on causation sounds reasonable in cases where intelligent beings are the causes.