In Book 13 of his work De Gloria et Honore Filii Hominis sup. Matth. the great Abbot, Rupert of Deutz, establishes that all things were created for Christ and goes on to give an excellent argument demonstrating that the primary motive of the Incarnation was by no means the remedy of man’s fall. Amazingly, the 1531 printing of the entire book can be found online and I took the liberty to take snapshots of the two pertinent passages (to see the passages in context and even the entire book, just click on the image).
[To see Pope Benedict XVI’s comments on the Christology of Abbot Rupert of Deutz click here. I’ve also put the video of Pope Benedict XVI on Abbot Rupert at the bottom of this post.]
From the Abbot’s pen (my translation):
Now in regard to this one should recall the extremely important and memorable chapter of the Apostle which says: For it became Him, for whom are all things, and by whom are all things, who had brought many children into glory, to perfect the Author of their salvation, by His passion (Heb 2:10). In the first place it should be asked whether this Son of God, to whom this passage refers, would have become man or not even if sin – as a result of which we die – were not to have taken place. Now that He would not have become a mortal man, that He would not have assumed a mortal body, unless man had fallen into sin – as a result of which we all become mortal – no one has any doubt, that is, unless he be an unparalleled infidel. Let us ask whether this future event [the Incarnation] was necessary to the human race in a different way, namely, that the God man should become head and king of all, which He now is; and what would be the response to this? Without a doubt it is certain of all the Saints and Elect that they would all have been born, and they alone, if the fall into sin of the first transgression had not occurred. Hence Father Augustine in the fourteenth book [Ch.23] of The City of God : “But he who says that there should have been neither copulation nor generation but for sin, virtually says that man’s sin was necessary to complete the number of the saints. For if these two by not sinning should have continued to live alone, because, as is supposed, they could not have begotten children had they not sinned, then certainly sin was necessary in order that there might be not only two but many righteous men. And if this cannot be maintained without absurdity, we must rather believe that the number of the saints fit to complete this most blessed city would have been as great though no one had sinned, as it is now that the grace of God gathers its citizens out of the multitude of sinners, so long as the children of this world generate and are generated.”
Therefore, there is no doubt that all the Saints and Elect would have been born right up to the number predetermined by the purpose of God who before sin blessed thus: “Increase and multiply” (Gen 1:28), and it would be absurd to hold that, on account of this blessing, sin was necessary in order for them to be born. Similarly, it would be absurd to hold that He who is the Head and King of all of the elect, both angels and men, would not have been born unless there had been sin as the most necessary cause. He came in order to be a man among men taking His delight through charity with the children of men. He is, therefore, that Wisdom of God of whom the Lord says in this regard: “The Lord possessed me in the beginning of His ways, before He made any thing from the beginning…” and concludes thus: “When He prepared the heavens, I was present… and my delights were to be with the children of men” (Prov 8).