Over the whole face of the land most manors were burthened with their own "customs," or special dues to the Crown: and it was for the purpose of ascertaining and recording these that William sent into each county the commissioners whose inquiries are preserved in Domesday Book. A jury empanelled in each hundred declared on oath the extent and nature of each estate, the names, number, condition of its inhabitants, its value before and after the Conquest, and the sums due from it to the Crown.

William found another check on the aggressive spirit of the feudal baronage in his organization of the Church. One of his earliest acts was to summon Lanfranc from Normandy to aid him in its reform; and the deposition of Stigand, which raised Lanfranc to the see of Canterbury, was followed by the removal of most of the English prelates and abbots, and by the appointment of Norman ecclesiastics in their place. The new archbishop did much to restore discipline, and William's own efforts were no doubt partly directed by a real desire for the religious improvement of his realm. "In choosing abbots and bishops," says a contemporary, "he considered not so much men's riches or power as their holiness and wisdom. He called together bishops and abbots and other wise counsellors in any vacancy, and by their advice inquired very carefully who was the best and wisest man, as well in divine things as in worldly, to rule the Church of God." But honest as they were, the King's reforms tended directly to the increase of the royal power.

The new bishops and abbots were cut off by their foreign origin from the flocks they ruled, while their popular influence was lessened by the removal of ecclesiastical cases from shire or hundred-court, where the bishop had sat side by side with the civil magistrate, to the separate court of the bishop himself. The change was pregnant with future trouble to the Crown; but for the moment it told mainly in removing the bishop from his traditional contact with the popular assembly, and in effacing the memory of the original equality of the religious with the civil power. The dependence of the Church on the royal power was strictly enforced. Homage was exacted from bishop as from baron. No royal tenant could be excommunicated without the King's leave. No synod could legislate without his previous assent and subsequent confirmation of its decrees. No papal letters could be received within the realm save by his permission. William firmly repudiated the claims which were now beginning to be put forward by the court of Rome. When Gregory VII. called on him to do fealty for his realm, the King sternly refused to admit the claim. "Fealty I have never willed to do, nor do I will to do it now.

I have never promised it, nor do I find that my predecessors did it to yours".

But the greatest safeguard of the crown lay in the wealth and personal power of the kings. Extensive as had been his grants to noble and soldier, William remained the greatest landowner in his realm. His rigid exaction of feudal dues added wealth to the great Hoard at Winchester, which had been begun by the spoil of the conquered. But William found a more ready source of revenue in the settlement of the Jewish traders, who followed him from Normandy, and who were enabled by the royal protection to establish themselves in separate quarters or "Jewries" of the chief towns of England. The Jew had no right or citizenship in the land; the Jewry in which he lived was, like the King's forest, exempt from the common law. He was simply the King's chattel, and his life and goods were absolutely at the King's mercy. But he was too valuable a possession to be lightly thrown away. A royal justiciary secured law to the Jewish merchant, who had no standing-ground in the local courts; his bonds were deposited for safety in a chamber of the royal palace at Westminster; he was protected against the popular hatred in the free exercise of his religion, and allowed to build synagogues and to direct his own ecclesiastical affairs by means of a chief Rabbi. That the presence of the Jew was, at least in the earlier years of his settlement, beneficial to the kingdom at large there can be little doubt.

His arrival was the arrival of a capitalist; and heavy as was the usury he necessarily exacted in the general insecurity of the time, his loans gave an impulse to industry such as England had never felt before. The century which followed the Conquest witnessed an outburst of architectural energy which covered the land with castles and cathedrals; but castle and cathedral alike owed their existence to the loans of the Jew. His own example gave a new direction to domestic architecture. The buildings which, as at Lincoln and S. Edmundsbury, still retain their title of "Jews' Houses" were almost the first houses of stone which superseded the mere hovels of the English burghers. Nor was the influence of the Jews simply industrial. Through their connection with the Jewish schools in Spain and the East they opened a way for the revival of physical science. A Jewish medical school seems to have existed at Oxford; Roger Bacon himself studied under English Rabbis. But to the kings the Jew was simply an engine of finance. The wealth which his industry accumulated was wrung from him whenever the Crown had need, and torture and imprisonment were resorted to if milder entreaties failed. It was the gold of the Jew that filled the royal exchequer at the outbreak of war or of revolt.

It was in the Hebrew coffers that the Norman kings found strength to hold their baronage at bay.