  Le Grand’s solution to the problem of how ideas represent their objects employed the notion of substitution or ‘supplying a stead’—wherein the cause (the object) contains all the properties found in the effect (the idea) not actually but in virtue of its ability to supply the substitute properties or proxies. And a relation, according to Le Grand, “…is nothing else but a mode of our understanding, comparing one thing with others, because of some properties or acts that are found in them” (1694, p. 17). Descartes himself never cashed out the notion of representation in terms of substitution, although he came close to suggesting it in the French version of the Third Meditation, in which he claimed that such things as extension, shape, position and movement may be contained in him eminently, “…and as it were the garments under which corporeal substance appears to us” (1985–91b, fn.1, p. 31). One could conceivably interpret this to mean that the garments of corporeal substance, namely extension, shape, position and movement are the garments supplied by the mind as the forms or the conceptions under which the mind grasps material things. Although the mind itself is not extended, shaped, locally positioned or moved, it dresses material substance in these properties in order to perceive particular material things. But there is no suggestion in Descartes regarding how the dressing is related to the material object grasped. Le Grand’s notion of substitution was intended as an explication of this relation, and is his contribution to the Cartesian dialectic on ideas.