The century of Rousseau enshrined nature as its ideal, its absolute value, the goal of its longing. Toward the end of this epoch, ego, the spiritual personality, emerged as a new central concept. Some thinkers represented the totality of being as a creation of the ego; others saw personal identity as a task, the essential task for man. Thus the ego, human individuality, appeared either as an absolute moral demand or as the metaphysical purpose of the world. Despite the colorful variety of its intellectual movements, the nineteenth century did not develop a comprehensive central idea—unless, perhaps, we give this title to the idea of society, which for many nineteenth-century thinkers epitomized the reality of life. Thus the individual was often seen as a mere point of intersection for social series, or even as a fiction like the atom. Alternately, complete submergence of the self in society was demanded; to devote oneself completely to society was viewed as an absolute obligation, which included morality and everything else. Only at the very end of the century did a new idea appear: the concept of life was raised to a central place, in which perceptions of reality were united with metaphysical, psychological, moral, and aesthetic values.

Georg Simmel, on individuality and social…, loc. 844