[freyr]

> I attribute it to the fact that they were natural experts

I agree that professors often choose books poorly, but disagree with the idea of a "natural expert." No human is born with a mathematical understanding of flight dynamics. There may be people who grasp it relatively quickly, although in my experience that's usually because they're relatively quick learners in general, and because they're building on a very strong foundation. Yes, there are people who are just smarter than the rest of us. But there are just as many people, if not more, who put in tremendous effort to become experts at which point they may appear as naturals. (Furthermore, some may downplay these effort and cultivate this idea that they're a "natural" to impress their colleagues and students.) It's not always obvious what sacrifices they made along the way.