Lawler's Rule

This quote shoots towards the top of my list:

"To laugh often and much; to win the respect of intelligent people and the affection of children; to earn the appreciation of honest critics and endure the betrayal of false friends; to appreciate beauty, to find the best in others; to leave the world a bit better, whether by a healthy child, a garden, or a redeemed social condition; to know even one life has breathed easier because you have lived. This is to have succeeded."
-Ralph Waldo Emerson

Two more solid quotes:

"Few men have virtue to withstand the highest bidder." -George Washington

"One of the penalties for refusing to participate in politics is that you end up being governed by your inferiors." -Plato

Via WILTW