Pretty much anything Mark Twain ever said. A sampling:
You can't depend on your eyes when your imagination is out of focus.
Twenty years from now you will be more disappointed by the things you didn’t do than by the ones you did do. So, throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.
Truth is stranger than Fiction, but it is because Fiction is obliged to stick to possibilities. Truth isn't.
Books are for people who wish they were somewhere else.
Life does not consist mainly, or even largely, of facts or happenings. It consist mainly of the storm of thoughts that is forever flowing through one’s head.
If you don’t read the newspaper, you’re uninformed. If you read the newspaper, you’re misinformed.
Only one thing is impossible for God: To find any sense in any copyright law on the planet.
Clothes make the man. Naked people have little or no influence on society.
Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great.