On Christian Doctrine 113The First Rule of Tichonius.

44. The first is about the Lord and His body, and it is this, that, knowing as we do that the head and the body--that is, Christ and His Church--are sometimes indicated to us under one person (for it is not in vain that it is said to believers, "Ye then are Abraham's seed," when there is but one seed of Abraham, and that is Christ), we need not be in a difficulty when a transition is made from the head to the body or from the body to the head, and yet no change made in the person spoken of. For a single person is represented as saying, "He hath decked me as a bridegroom with ornaments, and adorned me as a bride with jewels" and yet it is, of course, a matter for interpretation which of these two refers to the head and which to the body, that is, which to Christ and which to the Church.