“Quit majoring in the minor!”
“Simple can be harder than complex: you have to work hard to get your thinking clean to make it simple. But it’s worth it in the end because once you get there, you can move mountains.”
You can judge the quality of someone’s mind by the track record of their decisions over an extended period of time. If the record is consistent, then their mind is likely sharp. If it’s inconsistent, they have work to do.
The most important skill in your life is knowing how to think.