You're not stupid, it's just that some of the most intelligent people in the world have been drawn to the subject, most of which is actually quite new (consider

You're not stupid, it's just that some of the most intelligent people in the world have been drawn to the subject, most of which is actually quite new (consider that the atom was really only discovered in the 20th century!). The chains of inference are brilliant, and the amazing thing is how teachers treat the subject as a mundane set of tools to get through problem sets (not that David Morin does this). There's this air of understanding that isn't justified. As Feynman famously pointed out, forget about not understanding quantum mechanics - no-one really understands Maxwell's equations because to do so would be to somehow have an intuition for a function that maps each point in a volume of space to 6 numbers (the 3 components of the E and B vectors at each point). This intuition is impossible in the general case, but we fool ourselves into thinking we have that intuition because the pedagogy focuses on special cases. Anyway, don't be too hard on yourself. You are walking in the footsteps of some of the greatest minds in human history, and even though they've cleared a path, the going is still rather steep.