This papers considers the well-known tension between Locke’s definition of knowledge and his claim that we can know by sensation of the existence of things without the mind. I argue (in response to recent suggestions by Rickless and Newman) that sensitive knowledge is knowledge (and Knowledge with a capital ‘K’). I then present an account of sensitive knowledge that is consistent with Locke’s definition of knowledge, which gives a central role to the reflective idea of sensation. I conclude by considering whether Locke’s general epistemological framework leads inevitably to scepticism or idealism, arguing that Locke’s response to the sceptic is more interesting--and more robust--than it might initially appear.