"I now send it forth as a contribution to that Science of Human Nature, which has yet (as it seems to me) to be built-up on a much broader basis than any Philosopher has hitherto taken as his foundation. To the character of a System of Psychology, this treatise makes no pretension whatever; being simply designed to supplement existing Systems of Physiology and Metaphysics, by dealing with a group of subjects, which, occupying the border-ground between the two, have been almost entirely neglected in both. Hence in treating of Sensation, I have not entered into those details on the Physiology of the Senses which are readily accessible elsewhere; but have especially applied myself to the elucidation of the share which the Mind has, not only in the interpretation of Sense-impressions, but in the production of Sensorial states not less real to the Ego who experiences them than are those called-forth by external objects--a topic of the greatest importance in reference to the value of all Testimony given under a Mental preconception. And, in like manner, I have done no more than enumerate a large proportion of those principal modes of Mental activity, which are commonly designated as Intellectual Faculties, Propensities, and Emotions; in order that I might have space to bring into clear view that distinction between their automatic and their volitional operation, which has long appeared to me the only sound basis, on the one hand, for Education and Self-discipline, and, on the other, for that Scientific study of the various forms of abnormal Mental activity, which, rightly cultivated, is probably the most promising field of Psychological inquiry"--Preface. (PsycINFO Database Record (c) 2010 APA, all rights reserved).