Self-Interest
The principle of self-interest rightly understood is not a lofty one, but it is clear and sure. It does not aim at mighty objects, but it attains without excessive exertion all those at which it aims. As it lies within the reach of all capacities, everyone can without difficulty learn and retain it. 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 that excites them.
-- Alexis de Tocqueville
-- Alexis de Tocqueville