We can also express what we said at the end of last lecture in the following manner. Locke did not see the radical problem of cog- nition raised by ancient skepticism, and so this problem, naturally enough, is not the topic of his Essay. And yet the Essay purports to be a theory of the understanding, an epistemology—indeed an epistemology that is supposed to bring to an end the perpetual disputes of metaphysics, and to complete and perfect all the sciences through a clarification of the true meaning of their achievements and of the ultimate source of their basic concepts and methods.