I’m wrapping up The Warren Buffett Way by Robert Hagstrom for the second time. The first time I read it last year, I got a ton of information about the mechanics of how Warren Buffett invests. This time, I’ve gotten just as much, but more around psychology and mindset. It’s interesting how the book hasn’t changed, but what I got from it changed because what I’m interested in has changed.

The book helped me understand how a rational temperament is Buffett’s main competitive advantage. Here’s a passage that stuck with me:

The cornerstone of rationality is the ability to see past the present and analyze several possible scenarios, eventually making a deliberate choice. That, in a nutshell, is Warren Buffett.

Speaking to students at the University of Seattle, Buffett was asked how he got where he is and how he amassed such a large fortune. His response was thought provoking:

Buffett took a deep breath and began:

How I got here is pretty simple in my case. It is not IQ, I’m sure you will be glad to hear. The big thing is rationality. I always look at IQ and talent as representing the horsepower of the motor, but that the output—the efficiency with which the motor works—depends on rationality. A lot of people start out with 400-horsepower motors but only get 100 horsepower of output. It’s way better to have a 200-horsepower motor and get it all into output.

So why do smart people do things that interfere with getting the output they’re entitled to? It gets into the habits and character and temperament, and behaving in a rational manner. Not getting in your own way. As I have said, everybody here has the ability absolutely to do anything I do and much beyond. Some of you will, and some of you won’t. For those who won’t, it will be because you get in your own way, not because the world doesn’t allow you.

I’ve always thought high IQ is an edge. High mental acuity is genetic—you were either born with it or weren’t. But Buffett makes a great point about the efficiency with which someone uses their mental acuity materially impacting their output. You don’t have to be the smartest to win; you just need to avoid acting illogically.

You can’t change your IQ, but you can learn to think and act more rationally. This is a superpower hiding in plain sight. It’s something that everyone can do, but as with many superpowers hiding in plain sight, many people won’t.

Buffett built a fortune buying and overseeing businesses by being rational (he’s also pretty sharp). Entrepreneurs of all IQ levels should take note of his simple, but not easy, strategy and borrow a page from the Buffett playbook. Being rational and not shooting yourself in the foot is something everyone can do. It trumps intelligence in the long run and can lead to outsize success.