CHAPTER IV: QUESTION 2 —THE MODE OF THE UNION OF THE WORD INCARNATE (cont)
Twelfth Article: Whether The Grace Of Union Was Natural To The Man Christ
Cajetan remarks that this question concerns Christ, not as God, but as man. Is the grace of union natural to Him?
Reply. The grace of union is not natural to Christ, if this would mean that it is caused by the principle of the human nature; but it may be called natural inasmuch as it was bestowed upon Him together with the human nature, and moreover, inasmuch as it comes from the divine nature of Christ. Infused habitual grace in the soul of Christ is also natural in this sense.
The reason is that both graces are substantially supernatural and were given to Christ at the moment of His conception.
Doubt. Was the Blessed Virgin Mary the instrumental cause of the union of the human nature with the Word at the very moment of Christ's conception?
Reply. Most certainly no creature was or could be the principal efficient cause of the Incarnation, for the Incarnation is not only a work that belongs properly to God, such as creation, but it is His greatest work; for it is a miracle of the first order surpassing in substance all created and creatable powers and all exigencies of whatsoever created nature. It is also a mystery that transcends the mysteries of grace and that constitutes a special order, known as the hypostatic order.
The Incarnation was a work of the Trinity, by reason of omnipotence, which is a common attribute of the three persons. Thus, as we stated, the Father and the Holy Ghost joined in the act of uniting the human nature with the Word, but only the Son assumes or takes this nature to Himself.
But a doubt arises. Was the Blessed Virgin the instrumental cause of the Incarnation?
The question is disputed. St. Thomas says that Mary was not, for he writes: "In the conception of Christ, the Blessed Virgin took no active part, but was merely the material cause." But the instrumental cause takes an active part through the power of the principal agent.
Likewise St. Thomas maintains that there is no instrumental cause in creation, not even in the creation of the souls of infants, which occurs every day. The parents are not the efficient cause, but merely furnish the matter or dispose the body for the reception of the soul; a fortiori there is no instrumental cause in the Incarnation.
The principle on which this a fortiori argument rests may be illustrated by the following syllogism.
An instrument must dispose the subject for the effect of the principal agent. But, as in creation, there is no subject from which is produced that which is created from nothing; so in the Incarnation there is no pre-existing subject to be disposed, for the Incarnation is the communication of the personality of the Word to the human nature of Christ. The Word, however, is beyond the scope of created action, and is not the subject on which created action operates. Matter cannot be disposed for something uncreated, namely, for the Word that assumes. Therefore there is no instrumental cause in the Incarnation.
Hence, if the Blessed Virgin is said at times to be the instrumental cause of the creation of Christ's soul and even of the Incarnation, this must be understood in a broad sense, inasmuch as she provided the matter which was formed by the Holy Ghost into the human nature and united with the Word.