William James, The Principles of Psychology, Volume 1…
“ But which mode of consciousness of it is that which the psychologist must depend on? If to have feelings or thoughts in their immediacy were enough, babies in the cradle would be psychologists, and infallible ones. But the psychologist must not only have his mental states in their absolute veritableness, he must report them and write about them, name them, classify and compare them and trace their relations to other things. Whilst alive they are their own property; it is only post-mortem that they become his prey. ”
