(a particular aspect of the notion of social layer, from Sociology). A sociological category designating an important part of the social structure of modern society and of societies in transition from traditionalism and modernism. Encompasses the sectors situated between the upper and lower levels in the social pyramid, and contributes to social stability. The internal structure of the m.s. is quite contradictory. Its most dynamic and modern sector is composed of the levels that develop with progress in the technical-scientific and information fields (small-scale entrepreneurs with industrial workshops, farmers and livestock raisers, shop owners and consumer service providers, trained workers, professionals, etc.). Another sector is made up of the m.s. inherited from industrial society (skilled laborers, white-collar workers, farmers, etc.). An important segment of the m.s. is made up of public employees (teachers in schools and other educational institutions, salaried medical personnel, non-executive office workers, etc.). There are m.s. inherited from traditional society (artisans, journeymen, small business owners, transport services, service centers, small farmers, etc.). In the modernized countries, the m.s. make up the scaffolding of civil society, assuring its democratic development and social and political stability, and contributing to national consensus. These strata are forces that are more active, more dynamic, more open to innovation. In societies in transition, the role of the m.s. is contradictory and its social and political behavior cannot be characterized as homogeneous. While its more modern (and, incidentally, less numerous) sectors manifest dynamism and democratic tendencies in many situations, the traditional sectors are carriers of the propensity toward fundamentalism and right- and left-wing radicalism. In periods of crisis, the traditional m.s. can form the social base for autocratic and even totalitarian tendencies, aspiring to corporativist (*Corporativism), chauvinist (*chauvinism) and statist mentalities. Their conduct corresponds to the client-patron model. However, in this case we are dealing with m.s. that are impoverished and de-classed, ruined, that acquire personal experience in the practice of violence in the armed forces or paramilitary groups. This conduct is the consequence of participation in wars of depredation, colonialist adventures, civil wars, inter-ethnic and inter-faith conflicts. Parallel to this, m.s. are at the same time the most willing to assimilate the humanist traditions and to repudiate all manifestations of violence and injustice. The behavior of the m.s. in each situation is not fatally predetermined by their social condition; rather, it is the result of personal choices and the correlation of political and ideological forces.