 Newton’s scientific method provides Hume with a template for introducing the experimental method into his investigation of the mind. In An Enquiry concerning the Principles of Morals, he says he will follow “a very simple method” that he believes will bring about a transformation in the study of human nature. Following Newton’s example, he argues that we should “reject every system … however subtile or ingenious, which is not founded on fact and observation”, and accept only arguments derived from experience. When we inquire about human nature, since we are asking “a question of fact, not of abstract science”, we must rely on experience and observation (EPM 1.10/173–174).