There can be no doubt that the military tenure ... was itself introduced by the same gradual process which we have assumed in the case of the feudal usages in general. We have no light on the point from any original grant made by the Conqueror to a lay follower; but ... we cannot suppose it probable that such gifts were made on any expressed condition, or accepted with a distinct pledge to provide a certain contingent of knights for the king's service.[108] If my own conclusions be accepted, they will not only prove destructive of this view, but will restore, in its simplicity, a theory which removes all difficulties, and which paves the way to a reconsideration of other kindred problems, and to the study of that aspect of Anglo-Norman institutions in which they represent the feudal spirit developed on feudal lines. III. SCUTAGE, AID, AND 'DONUM' Precious for our purpose as are the _cartae_ of 1166, their evidence, as it stands, is incomplete. It needs to be supplemented by the early Pipe-Rolls of Henry II's reign. By collating these two authorities we obtain information which, singly, neither the one nor the other could afford. All those entries on the rolls which relate to _scutagia_, _auxilia_ or _dona_ require to be extracted and classified before we can form our conclusions. Hitherto, historians have remained content with repeating Swereford's _obiter dicta_, as extracted from the _Liber Rubeus_ by Madox, without checking these statements by the evidence of the rolls themselves. The question of Swereford's authority is one which it is absolutely necessary to deal with, because his statements have been freely accepted by successive historical writers, and have formed, indeed, the basis on which their conclusions rest. Now the presumption is naturally in favour of Swereford's knowledge of his subject. His introduction to the _Liber Rubeus_ is dated 1230, and he tells us that he had been at work among the records in the days of King John, under William of Ely[109] himself: he wrote with the actual rolls before him; he had been intimate with the leading officials of the exchequer, and enjoyed full knowledge of its practice and its traditions. I cannot wonder that, this being so, his positive assertions should have been readily believed, or that Mr Hall, when, for a short time, I was associated with him in preparing the Red Book for the press, should, with a kindly bias in favour of so venerable an authority, have shrunk from my drastic criticism of his famous introduction to that volume.