As social production develops, the human horizon expands, but the mere existence of social objects does not guarantee the continuity of this process. For N.H., continuity is a function of the interaction among human g. which transforms them in the process of production. These g., which promote continuity and development, are dynamic structures – they are social time in motion – without which a society would fall back into a state of nature and lose its condition of historical society, as occurred in the destructing of the ancient empires. Wars have been decisive factors in the “naturalization” of societies by destroying continuity through the violent decimation of the younger generation. Within a single temporal horizon, in a single historical moment, those who are contemporaries coincide, coexist, but do so from landscapes of formation that are specific to each generation by virtue of its difference in age from other g. This fact marks the enormous distance in perspective separating the g., which, though they occupy the same historical stage, do so from different situational and experiential “levels.” It also happens that in every historical time there coexist g. of different temporal levels, with different retentions (memories) and pretensions (or future plans), and which, therefore, form different situations. The bodies and behavior of children and the elderly reveal, for the active g., the presence of something they come from and toward which they are headed, and, in turn, for the young and old extremes of that triple relation, temporal circumstances that are also extreme. But this never remains fixed, because as the active g. grow old and the oldest g. die, children are gradually transformed and begin to occupy active, central positions. And new births continually reconstitute society. When, as an abstraction, one “detains” this incessant flow, it is possible to speak of a “historical moment” in which all the members occupying the same social stage can be considered contemporaries, living in a single time (in the sense of datability). But these members observe a non-homogeneous coetaneous ness (with respect to their internal temporarily and experience). The g. most contiguous to the active g. strive to occupy the central activity (the social present), in accordance with their particular interests, establishing a dialectic relationship with the g. in power in which we can observe the new surpassing the old. The topic of the g. has been treated by a number of authors, among whom Dromel, Lorenz, Petersen, Wechssler, Pinder, Drerup, Mannheimand, of course, Ortega y Gasset stand out.