"The intimate community of life and love which constitues the married state has been established by the Creator and endowed by him with its own proper laws...God himself is is the author of marriage." 

"The vocation to marriage is written in the very nature of man and woman as they came from the hand of the Creator. Marriage is not a purely human institution despite the many variations it may have undergone through the centuries in different cultures, social structures, and spiritual attitudes. These differences should not cause us to forget its common and permanent characteristics." (CCC 1603)