From Saint Alphonsus:
Many years ago a celebrated architect built a magnificent palace. When he had completed the costly edifice he gave it to some friends for their dwelling. But, these soon behaved badly, and became a scandal to the whole neighborhood. People often said: "Why was so splendid a palace erected for such wicked wretches?" At last the king arrived and took possession of the palace. He pardoned the servants and tried to make them good again. Then the people said: "Now we understand why this magnificent palace was built; it was for the king."
The architect in this parable is God the Father. He built a magnificent palace - the world. He put into it his friends - Adam and Eve. They soon behaved badly; and the angels asked, "Why was so splendid a palace - the world - created for these wicked people?"
At last the King, Jesus Christ, arrived. He pardoned the servants and tried to make them good again, and the angels exclaimed : "Now we understand why this great palace - the world - was made; it was for Jesus Christ, the King of the world."
God decreed from all eternity to create the world as a dwelling-place for men, where, by a holy life, they should gain an eternal reward. He foresaw from all eternity that men would not live up to the end of their creation. God would then have been frustrated in his design, had he not decreed from all eternity the Incarnation for the redemption of the human race. It was, therefore, principally for the sake of the God-Man that the world was created. He was to come for the justification and glorification of man.
Hence St. Thomas Aquinas says: Ordo naturae creatus est et institutus propter ordinem gratiae.
The principal end of the creation of the universe is, first, Jesus Christ, and, secondly, that the elect may receive here below the grace of God through Christ. Although it is true that the world existed before the Son of God became man, nevertheless, in the plan of creation and redemption, Jesus Christ is prior to the world. On this account St. Paul calls Jesus Christ the beginning, the first-born from the dead, that, in all things, he may hold the primacy: because in him it hath pleased the Father that all fulness should dwell, and through him to reconcile all things unto himself, making peace through the blood of the cross, both as to the things on earth, and the things that are in heaven. (Coloss. i. 18-20.)
There is, therefore, a certain intimate union between the creation of the world and the nativity of Christ. God did not wish that Christ should be born except in this world; and again, he did not wish that this world should exist without Jesus Christ. Nay, it was chiefly for his sake, as we have said, that God created the world and for his sake has preserved it and shall continue to preserve it to the end of time.
God had decreed to institute through him the order of grace, that is, the order of the justification and glorification of the elect.