I don't buy that at all. That attitude is precisely what makes people think they can't "get it". As if they lack some sort of natural aptitude or genetic predisposition towards numbers.
I don't know about genetic stuff, I'm just trying to make a relative statement between calculus and number theory.
Who knows what causes it, but there are a lot of smart 15 year olds who are less good at math than they are at most things. If those people really work their asses off at calculus, it works better than working their asses off at number theory. That's because calculus contains more memorization and less problem-solving.
"There is a widespread notion that 'ability' counts for more in learning mathematics than does effort. This is a doubtful notion, at best, and it has at least two bad consequences: it provides a recipe for failure and an excuse for failure when new ideas do not come easily."
