The current controversies about production and yields of medieval agriculture may give an outsider the impression that on this subject historians are more at variance than they actually are. Some historians may still cling to the Victorian belief that things economic were perpetually on the rise; historians thus minded are inclined to take it for granted that both the aggregate product of agriculture and agricultural output per head improved all through the Middle Ages. Other students, for example, Beveridge or Bennett, derived from the imperfectly selected data of the Bishop of Winchester's manors the impression that output per acre, and probably also per unit of seed, stayed put all through the Middle Ages. More recently other historians, including myself, have argued that output per acre tended to slump in the earlier, that is, pre-Black Death period, and may have picked up somewhat in the late fourteenth and fifteenth centuries. The concert of historians may therefore strike the ear as being even more cacophonous on this theme than on most other medieval themes.