  Le Grand’s account of sensations and ideas is orthodox Cartesianism. Sensory impressions are what mediate the external object and our mind’s idea of it, and they consist in nothing more than the immediate motions of the sensory organs in the body. Such motions are produced by a natural necessity and they share no similarity or affinity with the particular objects that cause them. Like Descartes, Le Grand used the example of the sword wounding the body to illustrate the non-resemblance or dissimilitude of the relations between external objects and sensations, and sensations and ideas. (1694, p. 327)  The sword that produces pain in us is nothing like our sensation or idea of pain, nor is our idea of pain anything like our sensation of pain. Yet, we maintain that there is a causal and representational relation between the sword and the idea it produces. In addition, Legrand like Descartes made a clear distinction between sensory impressions, which are particular, quantifiable motions, and ideas, which are representational or propositional in character. Given that sensations are non-resembling and non-representational (they are mere patterns of local motions) it follows that ideas, which are essentially representational, could not be derived from them. 