I argue that Leibniz’s doctrine of sensory representation is intended in part to close an explanatory gap in his philosophical system. Unlike the twentieth century explanatory gap, which stretches between neural states on one side and phenomenal character on the other, Leibniz’s gap lies between experiences of secondary qualities like color and taste and the objects that cause them. The problem is that the precise arrangement and distribution of such experiences can never be given a full explanation. In response, Leibniz (...) appeals to representation. I argue that the sense in which Leibnizian sensations are representations is too weak to close his explanatory gap. In the end, he must appeal to the doctrine of the best possible world. (shrink)