 The transition from Newton’s theory of gravity to Einstein’s illustrates this point. Einstein took it for granted that Newton’s theory of gravity (aided by perturbation theory) could account for 531 arc-second per century of the perturbation of Mercury’s perihelion. Not only were the empirical successes of Newton’s theory identified independently of the successor theory, but also some key theoretical components of Newton’s theory—the law of attraction and the claim that the gravitational effects from the planets on each other were a significant cause of the deviations from their predicted orbits—were taken to be broadly correct and explanatory (of at least part) of the successes. Einstein could clearly identify the sources of successes of Newton’s theory independently of his own alternative theory and it is precisely for this reason that he insisted that he had to recover Newton’s law of attraction (a key source of the Newtonian success) as a limiting case of his own GTR. He could then show that his new theory could do both: it could recover the (independently identified) sources of successes of Newton’s theory (in the form of the law of attraction) and account for its failures by identifying further causal factors (the curvature of space-time) that account for the discrepancies between the predicted orbits of planets (by Newton’s theory of gravity) and the observed  trajectories.[6]