Human beings need others in order to give form to their existence. A person's environment can be seen as a social system, with several characteristic variables, in which the person functions with others.
Human beings form social systems.
They are mutually dependent members of these systems. Nothing is naturally laid down in social systems. Their origin, operation and meaning are derived from the joint choices of the members who form the systems. Social systems make human functioning possible. Sometimes certain social systems are really disastrous for the development of one or more persons and these people become 'sick' through living in such a system.