If it's not in the computer, it doesn't exist.
Computers are unreliable, but humans are even more unreliable. Any system which depends on human reliability is unreliable.
Tell a person there are 500 billion stars in the universe and he'll believe you. Tell him a bench has wet paint and he'll have to touch it to be sure.
An expert is one who knows more and more about less and less until he knows absolutely everything about nothing.
Neither a borrower nor a lender be.
Logic is a systematic method of coming to the wrong conclusion with confidence.
You can never tell which way the train went by looking at the track.
If at first you don't succeed, put it out for beta test.
If I save time, when do I get it back?
I've got to sit down and work out where I stand.