An Enquiry Concerning The Principles Of Morals - pg. 155

If his heart rebel not against such pernicious maxims, if he feel no reluctance to the thoughts of villany or baseness, he has indeed lost a considerable motive to virtue; and we may expect, that his practice will be answerable to his speculation. But in all ingenuous natures, the antipathy to treachery and roguery is too strong to be counterbalanced by any views of profit or pecuniary advantage. Inward peace of mind, consciousness of integrity, a satisfactory review of our own conduct; these are circumstances very requisite to happiness, and will be cherished and cultivated by every honest man, who feels the importance of them.