With regard to the pain of want, I can discover no difference betwixt a generic and specific habit: the pain is the same in both. But these habits differ widely with respect to the positive pleasure. I have had occasion to observe, that the pleasure of a specific habit decays gradually till it become imperceptible. Not so the pleasure of a generic habit. So far as I can discover, this pleasure suffers little or no decay after it comes to its height. The variety of gratification preserves it entire. However it may be with other generic habits, the observation I am certain holds with respect to the pleasures of virtue and of knowledge. The pleasure of doing good has such an unbounded scope, and may be so variously gratified, that it can never decay. Science is equally unbounded; and our appetite for knowledge has an ample range of gratification, where discoveries are recommended by novelty, by variety, by utility, or by all of them.
Here is a large field of facts and experiments, and several phenomena unfolded, the causes of which have been occasionally suggested. The efficient cause of the power of custom over man, a fundamental point in the present chapter, has unhappily evaded my keenest search; and now I am reduced to hold it an original branch of the human constitution, though I have no better reason for my opinion, than that I cannot resolve it into any other principle. But with respect to the final cause, a point of still greater importance, I promise myself more success. It cannot indeed have escaped any thinking person, that the power of custom is a happy contrivance for our good. Exquisite pleasure produceth satiety: moderate pleasure becomes stronger by custom. Business is our province, and pleasure our relaxation only. Hence, satiety is necessary to check exquisite pleasures, which otherwise would ingross the mind, and unqualify us for business. On the other hand, habitual increase of moderate pleasure, and even conversion of pain into pleasure, are admirably contrived for disappointing the malice of Fortune, and for reconciling us to whatever course of life may be our lot:
How use doth breed a habit in a man! This shadowy desert, unfrequented woods, I better brook than flourishing peopled towns. Here I can sit alone, unseen of any, And to the nightingale’s complaining notes Tune my distresses, and record my woes. _Two Gentlemen of Verona, act 5. sc. 4._