This definition brings out all the elements of the social phenomenon and not merely those relating to the preservation and perpetuation of the species. For man is not solely matter; and the ends of the human species, far from being the materialistic ones we have in common with other animals, are, rather, and predominantly, the spiritual finalities which are peculiar to man and which every form of society strives to attain as well as its stage of social development allows. Thus the organization of every social group is more or less pervaded by the spiritual influxes of: unity of language, of culture, of religion, of tradition, of customs, and in general of feeling and of volition, which are as essential as the material elements: unity of economic interests, of living conditions, and of territory. The definition given above demonstrates another truth, which has been ignored by the political doctrines that for the last four centuries have been the foundations of political systems, viz., that the social concept has a biological aspect, because social groups are fractions of the human species, each one possessing a peculiar organization, a particular rank in the development of civilization with certain needs and appropriate ends, in short, a life which is really its own. If social groups are then fractions of the human species, they must possess the same fundamental traits of the human species, which means that they must be considered as a succession of generations and not as a collection of individuals. It is evident therefore that as the human species is not the total of the living human beings of the world, so the various social groups which compose it are not the sum of the several individuals which at a given moment belong to it, but rather the infinite series of the past, present, and future generations constituting it. And as the ends of the human species are not those of the several individuals living at a certain moment, being occasionally in direct opposition to them, so the ends of the various social groups are not necessarily those of the individuals that belong to the groups but may even possibly be in conflict with such ends, as one sees clearly whenever the preservation and the development of the species demand the sacrifice of the individual, to wit, in times of war.