In treating of grief, one is apt to be embarrassed by the abundance of documents, and the difficulty of being brief; in dealing with pleasure the contrary is the case. Are we to conclude that this is because, for centuries past, physicians have been collecting observations on pain, while there exists no profession having for its object the observation of pleasure? Or is it because humanity is so constituted as to suffer more from pain than it can enjoy from pleasure, and therefore studies everything relating to pain in order to find deliverance therefrom, while accepting everything agreeable naturally and without reflection? We cannot, however, accuse psychologists of having neglected this study, although the bibliography of Pleasure is very scanty compared with that of Pain. In general, they have considered these two subjects as complementary to one another, pleasure and pain being opposed to each other as contraries, so that the knowledge of the one implies the knowledge of the other. But this is only a hypothesis—perhaps true, perhaps false—resting in great part only on the testimony of consciousness, which is always open to question and never above suspicion. “It may be,” says Beaunis, very justly, “that pleasure and pain, which seem to us two opposite and mutually contradictory phenomena, may in the end be nothing but phenomena of the same nature, only differing in degree. It is possible that they may be phenomena of different orders, but incapable of such comparison with one another as would enable us to declare one contrary to the other. It is possible that they may depend simply on a difference of excitability in the nervous centres. Again, it is possible that they may be included, sometimes in one category, sometimes in the other.”[31] ----- Footnote 31: Beaunis, _Sensations internes_, chap. xxiii. ----- I.