Locke maintained that all knowledge is acquired and initially from the senses. All forms of nature can be explained mechanically by matter in motion and the impact of one body on another. Berkeley opposed this by denying the existence of inanimate matter and demonstrating that nothing exists save spiritual activity in God’s infinite mind and in human minds. Hume is the supreme sceptic. All our ideas are copied from our impressions. It is not reason which connects our ideas buts habits of mind. However hard we try we can never get away from ourselves and our perceptions.