Quaeritur: Is the Hypostatic Union an Accidental Union of Natures?

Quaeritur: Is the Hypostatic Union an Accidental Union of Natures?

Quaeritur: I have a question regarding the union of the Divine and human natures in the one Person of Christ. Is the union of the two natures in the one Person of Christ merely accidental or is it an essential union between the natures?  Is the union a quiddity onto itself?  How are we to conceive the nature of the union that occurs within the Person of the Incarnate Word?  I tried to word the question as best as I could.  Thank you, and God bless.

Respondeo: The hypostatic union is not an accidental union of natures, but is rather the closest union possible, that between a person/hypostasis/subject and his natures.  The hypostatic union is not a union that occurs between the natures themselves, but in the Person or Hypostasis of the Word.  So the human nature is united to the Person in the same way that the Divine Nature is united to the Person.  There is no direct essential union of the two natures among themselves, nor is there a third nature that unites them.  It is the person that is the "pivotal point" as it were, of the union.  So the two natures are united in the person, and so their union is not accidental, but, as St. Thomas says, it is a union "in subsistence":

A Divine Person is said to be incommunicable inasmuch as It cannot be predicated of several supposita, but nothing prevents several things being predicated of the Person. Hence it is not contrary to the nature of person to be communicated so as to subsist in several natures, for even in a created person several natures may concur accidentally, as in the person of one man we find quantity and quality. But this is proper to a Divine Person, on account of its infinity, that there should be a concourse of natures in it, not accidentally, but in subsistence. (ST IIIa, q. 3, a. 1, ad 2).

Ad secundum dicendum quod persona dicitur incommunicabilis inquantum non potest de pluribus suppositis praedicari. Nihil tamen prohibet plura de persona praedicari. Unde non est contra rationem personae sic communicari ut subsistat in pluribus naturis. Quia etiam in personam creatam possunt plures naturae concurrere accidentaliter, sicut in persona unius hominis invenitur quantitas et qualitas. Hoc autem est proprium divinae personae, propter eius infinitatem, ut fiat in ea concursus naturarum, non quidem accidentaliter, sed secundum subsistentiam.

The hypostatic union does produce an effect in the human nature which is accidental, yet profound: the human nature participates accidentally in the divine nature, becomes divinized by the fact that the Divine Nature is there present also (without confusing the two natures).  This is distinct from the fact that the human person is assumed by a Divine Person.  I'm speaking of the divinization that we also undergo, despite not having been assumed by a Divine Person.  So just as our own human nature receives a participation of the Divine Nature through the indwelling of the Holy Ghost in us, all the more so, the human nature of Jesus is divinized by the presence of the Divine Nature (aside of from is becoming the flesh of the Logos).  

I hope this helps (or at least that it doesn't confuse you further).