If you can't explain it to a six year old, you don't understand it yourself.
Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.
Never memorize something that you can look up.
A man should look for what is, and not for what he thinks should be.
Everything should be made as simple as possible, but not simpler.
I do not believe in the God of theology who rewards good and punishes evil.