The Son of God is the first-born of many brothers.
For to those who receive him he has given the power to become the sons of God.
He became the Son of man and made many men sons of God, uniting them to himself by his love and power, so that they became as one.
In themselves they are many by reason of their human descent, but in him they are one by divine rebirth.
The whole Christ and the unique Christ – the body and the head – are one: one because born of the same God in heaven, and of the same mother on earth.
They are many sons, yet one son. Head and members are one son, yet, many sons.
In the same way, Mary and the Church are one mother, yet more than one mother; one virgin, yet more than one virgin.
Both are mothers, both are virgins.
Each conceives of the same Spirit, without concupiscence.
Each gives birth to a child of God the Father, without sin.
Without any sin, Mary gave birth to Christ the head for the sake of his body.
By the forgiveness of every sin, the Church gave birth to the body, for the sake of its head.
Each is Christ’s mother, but neither gives birth to the whole Christ without the cooperation of the other.
In the inspired Scriptures, what is said in a universal sense of the virgin mother, the Church, is understood in an individual sense of the Virgin Mary.
And what is said in a particular sense of the virgin mother Mary is rightly understood in a general sense of the virgin mother, the Church.
When either is spoken of, the meaning can be understood of both, almost without qualification.
In a way, every Christian is also believed to be a bride of God’s Word, a mother of Christ, his daughter and sister, at once virginal and fruitful.
These words are used in a universal sense of the Church, in a special sense of Mary, in a particular sense of the individual Christian.
They are used by God’s Wisdom in person, the Word of the Father.
This is why Scripture says: I will dwell in the inheritance of the Lord.
The Lord’s inheritance is, in a general sense, the Church; in a special sense, Mary; in an individual sense, the Christian.
Christ dwelt for nine months in the tabernacle of Mary’s womb.
He dwells until the end of the ages in the tabernacle of the Church’s faith.
He will dwell forever in the knowledge and love of each faithful soul.
Isaac of Stella (1100-1169): Sermon 51, from the Office of Readings for Saturday of the Second Week of Advent @ Crossroads Initiative.