With the whole Church, and our long-sundered brethren the Copts, let us sing the praises of St Cyril, that pillar of the orthodox Faith, triumphant over foul Nestorius, who in demonic impiety refused to name Holy Mary as Mother of God, in opposition to the longheld piety of Christendom. His Collect tells the tale beautifully:
Deus, qui beatum Cyrillum Confessorum tuum atque Pontificem divinæ maternitatis beatissimæ Virginis Mariæ assertorem invictum effecisti: concede, ipso intercedente; ut, qui vere eam Genetricem Dei credimus, materna ejusdem protectione salvemur. Per eumdem Dominum...(O God, Who didst make blessed Cyril Thy Confessor and Pontiff an unconquered champion of the divine maternity of the most blessed Virgin Mary: concede, he intervening; that we, who believe her to be truly the Mother of God [Theotokos], may be saved through the maternal protection of the same. Through the same Our Lord Jesus Christ Thy Son...)
Yes, has been from all eternity God's Will, that we, saved by His Son the Word Incarnate of the Blessed Virgin, would have in her, whom He had made truly the Mother of God, a maternal protectress in Christ and under Christ for our salvation, and in Cyril and have in all the saints He has raised up, who by His grace have upheld these and all truths of the Faith, holy intercessors for us who adhere to the same Catholic belief.
This is the great axiom of causality: that considered in various modes, the First Cause (God - and His Christ the God-Man) and all secondary causes (the Blessed Virgin, the Saints) are each really causes of whatever is effected (our salvation).
As the Roman Church sings this night at Vespers:
O Doctor optime, Ecclesiæ sanctæ lumen, beate Cyrille,divinæ legis amator, deprecare pro nobis Filium Dei.O best Doctor, light of Holy Church, blessed Cyril,lover of the divine law, plead for us with the Son of God.