"Let no young man choosing the law for a calling for a moment yield to the vague popular belief that lawyers are necessarily dishonest. Resolve to be honest in all events; and if, in your own judgment, you cannot be an honest lawyer, resolve to be honest without being a lawyer. Choose some other occupation." -- Abraham Lincoln
Bonus: from Edward Murrow: "He was one of those civilized individuals who did not insist upon agreement with his political principles as a pre-condition for conversation or friendship."