Chapter 6, Footnote #04
Feelings of health
It may be thought, that in a certain degree of health, this negative account of the matter hardly comes up to the case. In a certain degree health, there is often such a kind of feeling diffused over the whole frame such a comfortable feel, or flow of spirits, as it is called, as may with propriety come under the head of positive pleasure. But without experiencing any such pleasurable feeling, if a man experience no painful one, he may be well enough said to be in health.