THOUGH it is subject, like all generalizations, to qualifications, it is substantially true to say that the English constitution, as it came slowly into shape during the remainder of the Middle Ages, was the product of three forces, represented by the king, the feudal overlords, and the subject people with their ineradicable traditions and way of life, implicit in what was comprehensively termed the ‘custom of the realm’. Through their interplay and through their influence upon one another the future was to be decided. If monarchy were strong, then, as in the past, it was in a position to provide the prime impulse, and, fortunately, the first two Norman rulers had put it on a firm basis. It was left to their successors to face the problem whether they could translate their large but ill-defined power into the form of institutions and thereby give it a recognized and legalistic framework.