It becomes a society only when the vitality of these contents attains the form of reciprocal influence; only when one individual has an effect, immediate or mediate, upon another, is mere spatial aggregation or temporal succession transformed into society. If, therefore, there is to be a science whose subject matter is society and nothing else, it must exclusively investigate these interactions, these kinds and forms of sociation.

DEFINE: Simmel defines society by reciprocal influence and 'sociation' rather than mere co-presence, establishing the foundational scope of sociology as the study of these interaction forms.

XREF: Connects to definitions of society/sociality in Durkheim and Weber; parallels the sociological concept that society is relational rather than aggregate.

Georg Simmel, on individuality and social…, loc. 196