Maimonides

If a person studies too much and exhausts his reflective powers, he will be confused, and will not be able to apprehend even that which had been within the power of his apprehension. For the powers of the body are all alike in this respect.

I don't believe in writer's block. Think about it - when you were blocked in college and had to write a paper, didn't it always manage to fix itself the night before the paper was due? Writer's block is having too much time on your hands.