Hahnemann distinguished 73 kinds of physical pain, Georget 38, Renaudin 12, etc. I give these numbers as curiosities. More recently Goldscheider (_Ueber den Schmerz_) establishes three stages in physical pain: (1) true, real (_echte_) pains; they depend on the nerves of special sensibility, and are caused by mechanical, thermal, or chemical stimulations, by inflammation and poisons; (2) indirect pains, pseudo-pains, which consist especially in a state of discomfort (_Schmerzweh_); in the case of the head, stomach, etc., they may be as oppressive and cause as much torture as “real” pains; (3) psychic or ideal (_ideel_) pains, which are a hyperæsthesia of the sensitive activity; they are met with in neuroses (neurasthenia, hysteria, hypochondria), in hallucinations, the hypnotic state, etc. This classification is perhaps acceptable in physiology. For psychology, every pain, in virtue of being a fact of consciousness, is “true” and “real.” ----- The question still remains why certain representations have the unfortunate privilege of arousing pain. This is a question which I can only touch on, because it belongs to another part of the subject. For the moment I simply reply that it is because they are the beginning of mental disorganisation, just as physical pain is the beginning of physical disorganisation. The sentient being, man or animal, is a bundle of needs, of appetites, of physical or psychic tendencies; everything that suppresses or impedes them is translated into pain. Physical suffering is the blind and unconscious reaction of the organism to every hurtful action. Grief is the conscious reaction to every decrease of psychic life. The man shut in by narrow and commonplace surroundings would certainly feel no æsthetic pain, because having no need of æsthetic satisfaction he could not be impoverished or impeded by its absence. In short, pain under all its forms reveals an identical nature. The distinction between physical pain and moral pain is practical, not scientific. CHAPTER III. PLEASURE. _Subject little studied—Is Pleasure a sensation or a quality?—Its physical concomitants: circulation, respiration, movements—Pleasure, like pain, is separable: physical and moral anhedonia—Identity of the different forms of pleasure—The alleged transformation of pleasure into pain—Common ground of the two states—Hypothesis of a difference in kind and in degree—Simultaneity of two opposite processes: what falls under consciousness is the result of a difference—Physiological facts in support of the above._