Kant's account of Newtonian science in terms of a priori structures of the mind has been generally interpreted as too restrictive. If Newtonian science is an instantiation of the system of categories, then, in order to retain any value, they need to be dynamized in accordance with the development of science beyond Newton. This paper suggests that the restriction in best understood as Kant attempt to provide a primary matrix of sense for any possible natural science, inasmuch as it reflects the “first idea” contained in the Copernican Revolution.