Math

(via Paul Graham)

I found, when I was studying mathematics, that 2 things were true: (1) the teacher was not too good and (2) the book was not too good. So I would always buy a half-dozen books on the topic and try to get the full picture by reading the same sections in each book. The combination helped me understand much more than the sum of the content. Also, I was never opposed to reading something as much as 10 times until I squeezed everything out of it.

I had the same problem, but I was not as diligent in overcoming it.