Marriage
It is completely appropriate that marriage should have been brought within the sacramental structure of the Church. It is one of the high moments in the life of individuals; it is the foundation of the family, the basic unit of human social life. Grace is not just something to fall back on in the crises of life - its place is at the centre and the foundation of daily life in the family.
The visible aspects of this sacrament are in the giving and receiving of a ring (or rings) and the exchange of vows, again with the grace of God for these specific people in their vocation of marriage being seen as the spiritual aspect. In marriage the function of the Church is largely that of witness as an action takes place before God.