continued, will surely, in ordinary cases, use up the surplus and then bring about the conditions which give pain. It is a notable corroboration of my theory that the process is not reversed. Pain caused by excess in activity does not go over into pleasure, with unchanged content, unless there supervenes rest, i.e., opportunity for recuperation and storage in the organ which has been active.
13. That increase of the stimulus which is giving pleasure increases the pleasure for a time, then diminishes it, and then produces an increasing pain, is quite in accordance with the notion that something is used up (with pleasure experience) before we can get the organ which is active into the condition in which it becomes capable of giving pain.
14. Under our hypothesis we do not need to look for any special environmental stimulus-differentiation corresponding with pleasure and pain, as we did under the sensational view, if the hypothetical pleasure and pain senses are to fall in line with all other sensations; for under our hypothesis pleasure and pain are determined by relations within the organism which are general and which occur with all differentiations of environmental action upon us.
15. We are not surprised, when we consider the great variations of nutritive conditions, that a mental element which at one time brings us pleasure on some other day brings us pain, or vice versa, with no change of stimulation. The capacity to bring conscious pleasure or conscious pain after very long intervals is also quite explicable without supposing any such non-activity as would imply atrophy of the organ which finally acts pleasurably or painfully.
That the phenomena of habit are found to be a corollary from the general theory, I have argued at some length in Mind, No. 64. The action which is painful to-day but not carried too far calls for an unusual supply of nutriment, and this develops a capacity for pleasure-giving at the next moment of stimulation. This pleasure capacity may increase largely by continuous repetition of this process.
The pains which first bring to our notice the existence of
