Hans Morgenthau quotes George Washington on the primacy of self-interest:

A small knowledge of human nature will convince us, that, with far the greatest part of mankind, interest is the governing principle; and that, almost, every man is more or less, under its influence. Motives of public virtue may for a time, or in particular instances, actuate men to the observance of a conduct purely disinterested; but they are not of themselves sufficient to produce persevering conformity to the refined dictates and obligations of social duty. Few men are capable of making a continual sacrifice of all views of private interest, or advantage, to the common good. It is vain to exclaim against the depravity of human nature on this account; the fact is so, the experience of every age and nation has proved it and we must in a great measure, change the constitution of man, before we can make it otherwise. No institution, not built on the presumptive truth of these maxims can succeed.

Source - letter from Washington on reforms to the Continental Army, written in January 1778 at Valley Forge.