The story teaches us that insufficient knowledge is always dangerous.
The short story "The Monkey's Paw" has several messages for readers:
1. Be wary of anything that is too easy/free. If you don't have to work for it, there is usually a catch.
2. Be careful what you ask for, you may just get it. It's best to appreciate the things you have rather than constantly pine for what you don't. If you spend too much time hoping and wishing for a better, easier, happier life you'll miss out on the best moments of the life you already lead
3. Don't mess with the natural order of the universe. You'll get what you deserve and work for in life. Don't touch things that don't belong to you. Chi! Karma! The Golden Rule! Whatever you want to call it, the universe has its own momentum and trying to "trick" it will have devastating results.
4. Two wrongs will never make a right. When you discover that your greed has killed your son chances are he won't be happy when you turn him into a zombie.