In the supernatural order, the Church, after the manner of our blessed Lord, takes hold of this permanent character of love in the order of nature and elevates the promise “I do” to the dignity of a sacrament.
The love that is always expressing itself in terms of the eternal, and articulating itself in such phrases as “till the sands of the desert grow cold,” the Church seizes and refines by finding a symbol of love more abiding still than even the sands of the desert. She goes to the most personal, permanent, and unbreakable union of love the world has ever known — namely, the love of Christ for human nature — and during the solemnity of the nuptial Mass reminds the young couple that they are to love one another with the same indissoluble love with which our blessed Lord loved the human nature that He took from the womb of the Blessed Mother.
That love which desires to express itself in terms of the permanent, the Church models on the great prototype of the marriage of God and man in the Incarnation of our Lord and Savior, Jesus Christ. When God veiled the awful terror of His glory, descended into the flesh-girt paradise of Mary, and assumed human nature, He assumed it, not for an earthly life stretching from crib to Cross, but permanently and eternally through the risen life of Easter Sunday and the glorious Ascension to the right hand of the Father.
Now, since Christian marriage of flesh and flesh is modeled upon the permanent marriage of God and man, the Church says that it, too, must take on for life the character of permanence and indissolubility. As the womb of the Blessed Mother was the anvil of flesh upon which the divine and human natures of Christ were united under the Pentecostal flame of the Holy Spirit in the unity of the Person, so, too, the nuptial altar becomes the new anvil whereon two loving hearts are fused and joined by a flame of the sacramental Spirit in the unity of the flesh.
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