The Byzantine social formation consisted overwhelmingly of peasant producers. The fundamental characteristic of the peasantry is that the family is the most important unit of production and it has effective control (but not necessarily ownership) of the means of production. Peasant families are usually associated in larger groups with certain collective interests which may vary from one society to another. The family forms a socio-economic unit and depends mainly on the labour of its own members. Additional labourers, when necessary, are usually obtained from the same community and belong to the same social class. The familial units produce mainly for their own subsistence. Some artisanal activity may occur in the village, but it is still a household activity and these artisans are derived from the peasantry and usually combine their industrial activity with agriculture. They produce for consumption within the village, not exchange outside the village. Peasant producers formed the economic base of Byzantine society. Their own requirements were not restricted to consumption needs, but included the storage of sufficient seed for next year's crop and the provision of food for livestock. They also had to replace their instruments of production whenever necessary. Peasant production depended on a balance between needs and a distaste for manual labour which restricts the intensity of agricultural production (at least when land is not in short supply). Once enough is being produced to satisfy needs there is little incentive to extend cultivation further, unless pressure is put on the peasant community by some outside authority to alienate part of its produce. The production of a surplus was essential for economic development (although on its own insufficient for this purpose).