But in whatever way the tranquillity which looks like indifference is brought about, it is still a pleasurable condition. Or if the state of apparent indifference be a state of ennui and satiety, in that case it is a condition of pain. A sensation which was absolutely indifferent to us would be no sensation; it would not be felt at all. All sensations then, even those which seem to be indifferent, involve either pleasure or pain as their constant and inseparable ingredient.
16. Sensation, and the capacity of receiving it, being, according to this psychology, the only original quality or endowment of our nature; and sensation being always an expression either of pleasure or of pain, and the sensational capacity being a susceptibility of these feelings, it follows that pleasure and pain, and a susceptibility thereof, form originally the whole staple and essence of our constitution.
17. The second characteristic of sensation is, that it is strictly individual or particular. This characteristic of sensation is very important, but it is less obvious and has been less noticed than the other. Indeed, I am not aware that it has been noticed at all by any psychological observer. But it is a quality of sensation which it is very necessary to keep in view, if we would understand in their true form the ethics which have their origin in the psychology of sensation. By the neglect to note and signalise this characteristic of sensation, the true aspect of the
