A person has three choices in life. You can swim against the tide and get exhausted, or you can tread water and let the tide sweep you away, or you can swim with the tide, and let it take you where it wants you to go.
Diane Frolov and Andrew Schneider, Northern Exposure, Northern Lights, 1993
When you point your finger at someone, three fingers are pointing back at you.
When you make a mistake, there are only three things you should ever do about it: admit it, learn from it, and don't repeat it.
Paul "Bear" Bryant, I Ain't Never Been Nothing but a Winner
To the uneducated, an A is just three sticks.
Pooh's Little Instruction Book, inspired by A. A. Milne