By association with others in a family, the human person begins the process of socialization. That process continues on through school and work and all the stages of life. It continues for all by association with others in social institutions that foster growth, protect dignity, and promote the common good. This is how human persons achieve their fulfillment in relationships with others, in companionship with others. That was just one of the many divisions that Jesus wanted to close.
Association brings people together.
By association, individuals overcome isolation. If association is denied, the path to a fuller life is foreclosed. Phone books list all kinds of associations. They reflect an impressively broad range of human activity. There are associations that use other labels like league, union, federation, council, or conference.