The Church is the body of Christ.
The Church is a body; it is the body of Christ. He took a new body. For his physical body he now uses a social body, an ecclesial body. Just as my own body is made up of millions and millions of cells and vivified by one soul, governed by a visible head, and presided over by an invisible mind, so too all of us who have in any way become incorporated to Christ are the cells in his body. We are one, because we are vivified by one soul, which is the Holy Spirit; we are presided over by the invisible head, Christ in heaven, who is the head of the body, and we are governed by the visible head, our Holy Father. That is the Church. At the Vatican Council, we defined the Church as the mystery, and that's what it is. It is the great sacrament of sacraments because it has something physical about it and something invisible about it.