This chapter presents the instance view, and used it in conjunction with the Structuralist analysis of physical theories to produce an account of physical explanation. The basic idea is that the world comprises physical objects that exhibit quantities and that there are patterns or laws of nature constituted by correspondences between quantities. The partial potential models of a theory are ‘sharp’ in the sense that their component function values are real numbers. The technical device which BMS introduce in their discussion of approximation is called a blur and it is constructed on the basis of the topological notion of a uniform structure or uniformity on a set. As well as providing further demonstration of the power of the Structuralist approach, this also serves to support the ontic conception of explanation by showing that it can help resolve substantial problems in the theory of explanation.