Knowledge
Knowledge is one and only one thing: Your capacity to act.
If you aren’t doing the thing you say you can do, you don’t know how to do it. You don’t have that knowledge.
If you’ve never lifted 200 lbs on the bench press, no matter what you think you know about lifting weights, you don’t know how to lift 200 lbs.
If you’ve never built a profitable business, then you don’t know how to build a profitable business.
If 1,000 people haven’t bought a product you’re selling, you don’t know how to get 1,000 people to buy a product.
Don’t kid yourself. The information you put in your brain that came from books or blogs or encyclopedias is completely meaningless until an action is taken and a result is produced.
I’ve found all other contradictions to this principle to be completely useless.