The word brit is most widely known as the name for the circumcision ceremony which Jewish boys undergo, normally at eight days old. It is also called the "brit shel Avraham Avinu" - "the covenant of Abraham, our Father" - after Abraham, to whom the mitzvah of circumcision was first given, (Genesis 17:10); and brit milah (milah also means "word.").
The word brit is literally translated as "circle, ring" or "chain." From these senses, brit derives its main meaning of "covenant," a binding agreement between two parties. Brit in this sense is at the heart of Judaism.
God made covenants with Abraham, Isaac and Jacob, and with the Jewish people as a whole at Mount Sinai and on the planes of Moab, as they were about to enter the Land of Israel. The content of the covenant was that we agreed to be partners with God in perfecting the world, while God agreed to maintain us as his eternal, chosen people.
In his writings on the subject, Chief Rabbi Dr Jonathan Sacks shows how the idea of a brit was one of the most original Jewish contributions to world thought. As he puts it: "A brit is made when free agents, respecting one another's freedom, bind themselves by a mutual promise to work together, to be loyal to one another, and to achieve together what neither can achieve alone."
It is not an agreement to be set aside when convenient, but one which constitutes who we are. Marriage at its best is the most tangible everyday example of brit.