236 THE HISTORY OF MEDIEVAL EUROPE these expressions seem not to have indicated any exact area, but to have varied in different places and according to the fertility of the soil. In some parts of Europe the population was too sparse or the country too difficult for large estates cultivated by serfs, and we find single houses and farms. But the villa was the rule. Normally the lands divided among the serfs aggregated more than the mansus indominicatus, or demesne lands reserved by the lord ; and as time went on the lord distributed more and more of his land to tenants, probably because the population increased and because he found the method of having the peasants pay him a portion of their crops more satisfactory both to him and to them than having them work on his land, which required overseers or they would work none too well. On many villas and manors the serf's holding was not a single, compact plot of land and enclosed farm, but consisted of several scattered fields and meadows and vineyard. Nor did every peasant possess a plough of his own, since the number of ploughs on a manor was often considerably less than the number of tenants and serfs. It seems evident, therefore, that the peasants ploughed their fields together, since there were no fences in the way. In those days they did not raise nearly so many different things from the soil as we do to-day. Clover, beets, potatoes, and many other agricultural products were unknown. Scientific farming, irrigation, and fertilizing were little known or practiced. Therefore the lack of variety in the crops soon impover- ished the soil, and a very general custom was to let a field lie fallow every other or every third year, in order that it might recover its fertility. Consequently each peasant needed to have several strips of arable land scattered through the large fields which the peasants ploughed to- gether, in order that while some of his land remained un- tilled he might get his subsistence from the rest. The land reserved for the lord was sometimes scattered in strips among the holdings of the peasants, and sometimes con- sisted of separate fields. Then there were common lands p here serfs and lord alike might pasture their cattle or send
