"We have now, therefore, two distinct divisions of Consciousness: _Sensation_, which as before consists only of pleasure and pain, though now of different kinds; and _Perception_, which classifies states of consciousness and their relations, and is therefore concerned only with change. Knowledge, therefore, has originally no other object than different pleasures and pains, but eventually it attends so much to the differences and resemblances that it ceases to remember the pleasure or pain; in its absorption in the relation it well-nigh forgets the things related. This process is furthered by the fact that, as the medium gets more extended, each part of it has less average effect upon the organism: the primary pleasures and pains being spread over a larger surface are less intense, and so obtrude themselves less. This is exemplified by the common observation that sensation and perception tend to exclude each other.... Nevertheless pleasure and pain ever remain indissolubly connected with consciousness, though their presence is often unheeded, and only the more violent forms force themselves on the attention. "What is true of these simple forms of consciousness, is true of their later development. The relation of sensation to perception is the same as that between the faculties of which these are respectively the germs, emotion and intellect. For emotion is associated sensations of pleasure and pain; and intellect is associated perceptions of change and relation. Hence by their very nature these are at once mutually exclusive and inseparable. A strong emotion drives out reason, and much reasoning chills emotion.... Yet we can give _some_ reason for any emotion; and we feel some emotion in working a mathematical problem.... In every intentional act it is evident that both are involved; the end being given by emotion, the means by reasoning. Reasoning can give no end, it can only arrange, elicit, suggest; emotion can give no means, for it cannot classify or observe relations. In the building up, therefore, of any moral faculty, both these elements must take a part. Hence it will be well to trace, a little more closely, their mode of formation, and their connection with muscular activity. "When in the course of experience a certain sequence of sensation frequently recurs, the consciousness becomes habituated to it, and the return of the first sensation is followed by an idea or associative image of the others.... Hence the idea of pleasure or pain not actually felt comes to be associated with objects, which, if placed in certain different positions, would effect us in the way imagined.... Pleasure may thus be associated through a train of ideas of any length.... After a time this process becomes organic, the intermediate terms are lost, and pleasure is _directly_ connected with sensations and ideas that are in themselves not distinctly pleasurable.