“Feynman's grasp of the big picture, coupled with his love for knowing first-hand of practical details - from low-level programming to lock-picking - gave him an almost unique perspective on any subject he chose to study. It was this mastery, both of the minutiae of a subject and of its overall intellectual framework, that gave him the seemingly effortless ability to move back and forth between the two levels at will, without getting lost in the detail or losing the overall plot.”

Source: Wikiquote