“Be ashamed to die until you have won some victory for humanity.”- Horace Mann, address at Antioch College, 1859
It doesn't trump my favorite quote:
“Don't say you don't have enough time. You have exactly the same number of hours per day that were given to Helen Keller, Pasteur, Michelangelo, Mother Teresa, Leonardo da Vinci, Thomas Jefferson, and Albert Einstein.” -H. Jackson Brown, Jr.
… but it comes close.