Similar quotesI have never met a man so ignorant that I couldn't learn something from him.
Galileo Galilei 
Youth is a wonderful thing. What a crime to waste it on children.
George Bernard Shaw 
You do not really understand something unless you can explain it to your grandmother.
Albert Einstein 
Age is an issue of mind over matter. If you don't mind, it doesn't matter.
Mark Twain 
Those that know, do. Those that understand, teach.
Aristotle 