he is famous for saying that "no matter what difficulties you have in mathematics, I can assure you, mine are more severe". Obviously, he was not an idiot, and indeed a very good mathematician. But is real brilliance came from being able to understand and see beyond the physical world around us. He struggled with complex maths involved in general relativity (and that's why it took him soo long to publish) - so it's hope for all budding physicists out there who don't instantly grasp the complex maths involved in physics today!