"I will tell you what the game of checkers teaches us. We learn the following rules: 1. You give up one piece to save two. 2. You cannot make two moves at once. 3. You are not allowed to have regrets. 4. You only go ahead, you do not retreat. 5. Once you go up, the way is open on all sides."
January 1, 1970
https://en.wikiquote.org/wiki/Menachem_Nochum_Friedman