Domesday Book and Beyond

"[...]to know whether that value had been rising or falling during the past twenty years. Domesday Book has well been called a rate book, and the task of spelling out a land law from the particulars that it states is not unlike the task that would lie before any one who endeavoured to construct our modern law of real property out of rate books, income tax returns and similar materials. All the lands, all the land-holders of England may be brought before us, but we are told only of such facts, such rights, such legal relationships as bear on the actual or potential payment of geld. True, that some minor purposes may be achieved by the king's commissioners, though the quest for geld is their one main object. About the rents and renders due from his own demesne manors the king may thus obtain some valuable information. Also he may learn, as it were by the way, whether any of his barons or other men have presumed to occupy, to 'invade, '[...].