2 Assuming that what we ask is for the best, our eagerness to obtain it is nothing to be ashamed of. And if all the Scriptures agree with our view, we are not too bold in urging you to a course to which you have yourself often urged us.
What are God's first words to Abraham? “Get you out of your country and from your kindred unto a land that I will show you.” The patriarch— the first to receive a promise of Christ— is here told to leave the Chaldees, to leave the city of confusion and its rehoboth or broad places; to leave also the plain of Shinar, where the tower of pride had been raised to heaven. He has to pass through the waves of this world, and to ford its rivers; those by which the saints sat down and wept when they remembered Zion, and Chebar's flood, whence Ezekiel was carried to Jerusalem by the hair of his head. All this Abraham undergoes that he may dwell in a land of promise watered from above, and not like Egypt, from below, no producer of herbs for the weak and ailing, but a land that looks for the early and the latter rain from heaven. It is a land of hills and valleys, and stands high above the sea. The attractions of the world it entirely wants, but its spiritual attractions are for this all the greater. Mary, the mother of the Lord, left the lowlands and made her way to the hill country, when, after receiving the angel's message, she realized that she bore within her womb the Son of God. When of old the Philistines had been overcome, when their devilish audacity had been smitten, when their champion had fallen on his face to the earth, it was from this city that there went forth a procession of jubilant souls, a harmonious choir to sing our David's victory over tens of thousands. Here, too, it was that the angel grasped his sword, and while he laid waste the whole of the ungodly city, marked out the temple of the Lord in the threshing floor of Ornan, king of the Jebusites. Thus early was it made plain that Christ's church would grow up, not in Israel, but among the Gentiles. Turn back to Genesis, and you will find that this was the city over which Melchizedek held sway, that king of Salem who, as a type of Christ, offered to Abraham bread and wine, and even then consecrated the mystery which Christians consecrate in the body and blood of the Saviour.
Source: Letters (New Advent)