 Arnauld developed a general account of sensory ideas that builds on this part of Descartes’ reply. He sets out his account clearly in aIdeas: Sensory ideas, like the idea of pain and the idea of cold, are perceptions of mental states. Taken apart from the judgments in which we falsely identify these mental states with states of material things, sensory ideas are clear and distinct. They become confused, and hence obscure, only as a result of the precipitous, false judgments of childhood. Arnauld quotes Descartes’ Principles of Philosophy, Part I, #68 in support of his account: