Thirdly, they could serve as material for the guidance of agitators, because conditions of labor change relatively slowly and the principal demands of the workers in a given trade hardly ever change (see, for example, the demands advanced by the weavers in the Moscow district in and in the St. Petersburg district in ); a compilation of these demands and needs might serve for years as an excellent handbook for agitators on economic questions in backward localities or among backward strata of the workers.