Combinatorics is like the art of counting without actually counting.
一人独处应谨慎自己的行为,预知每一心思所含的意念,严肃威仪安于天命,敬人伦以成圣贤,谨慎各种行为以成就德引,改过向善以成贤良。
Complexity is easy, simplicity is hard.