By its admirable conformity to human weaknesses, it easily obtains great dominion; nor is that dominion precarious, since the principle checks one personal interest by another, and uses, to direct the passions, the very same instrument which excites them.

The principle of interest rightly understood produces no great acts of self-sacrifice, but it suggests daily small acts of self-denial.

By itself it cannot suffice to make a man virtuous, but it disciplines a number of citizens in habits of regularity, temperance, moderation, foresight, self-command; and, if it does not lead men straight to virtue by the will, it gradually draws them in that direction by their habits.

If the principle of interest rightly understood were to sway the whole moral world, extraordinary virtues would doubtless be more rare; but I think that gross depravity would then also be less common.

The principle of interest rightly understood perhaps prevents some men from rising far above the level of mankind; but a great number of other men, who were falling far below it, are caught and restrained by it.