  Underlying much of Locke’s attack is the Cartesian view that to claim something is ‘in the mind’, innately or not, is to give it a place in our conscious awareness. Leibniz’s bold hypothesis of non-conscious mental states would, if successful, sweep aside most of Locke’s arguments against innateness. But we need to keep in mind that the polemics in the Essay, though they were historically influential, are almost a sideshow. The real issue is whether the Empiricist can construct a satisfactory account of human knowledge without adverting to any innate ideas and principles. To meet this challenge, Locke (and to an even greater extent Hume) offered what may be termed adequacy of the stimulus counterarguments. Locke constructs a theory of experience (perception and reflection) as the source of all our ideas, sketches an account of the mental faculties that can be brought to bear on these ideas, and applies these materials to our ideas of infinity, number, space, substance, our understanding of general principles of causality, and so on. These were the abstract ideas and principles that Rationalists had claimed could not be derived from perceptual experience. Locke wants to demonstrate that such ideas and principles can be acquired without the need for any innate ‘pre-seeding’. Locke believes that the key to intelligibility and understanding lies in a proper appreciation of what our faculty of Reason can accomplish when set to work on the ideas received in our experience.