And it keeps accumulating — you get to an advanced class, all of a sudden you hit a wall and say, "" I'm not meant to be a cancer researcher; not meant to be a physicist; not meant to be a mathematician. "" I suspect that that actually is the case, but if you were allowed to be operating in a mastery framework, if you were allowed to really take agency over your learning, and when you get something wrong, embrace it — view that failure as a moment of learning — that number, the percent that could really master calculus or understand organic chemistry,