"All knowledge of reality starts from experience and ends in it." But he immediately proceeded to emphasize the role that "pure reason" and logical deductions play. He conceded, without apology, that his success using tensor calculus to come up with the equations of general relativity had converted him to a faith in a mathematical approach, one that emphasized the simplicity and elegance of equations more than the role of experience. The fact that this method paid off in general relativity, he said, "justifies us in believing that nature is the realization of the simplest conceivable mathematical ideas."45"