Bede : So Abram departed as the Lord had directed him, and Lot went with him. Abram was seventy-five years old when he left Haran. It is clear from this number of Abraham's years that he left Haran while his father was still alive, as was explained above. There is no doubt that the number seventy-five is mystical, since in it he received the promise of divine blessing and left Isaac, the heir of the same blessing, when he was dying. To speak briefly, seventy, because it is seven times ten, represents the perfection of good actions, when we fulfill the commandments of the Decalogue through the grace of the Holy Spirit, which the prophet describes as sevenfold. To these are added five, so that in all the senses of our body, we may fulfill the same divine commandments with the help of the Spirit's grace. Abram was seventy-five years old when he left Haran at the command or promise of the Lord and entered the Promised Land; to show that he himself, through the help of the Spirit, having anathematized the errors of Babylonian conduct, would keep God's commandments; and this in all that he did with his body, whether living, hearing, tasting, or touching, so that there might be nothing in his body that was not enlightened and aided by the gift of the Spirit to obey the heavenly commands. And he marked that all his heirs of the promise should live in a similar manner. It is also to be imitated by all the sons of the promise, among whom we are, that he was ordered to leave his land, his kindred, and his father's house. For we depart from our land when we renounce the pleasures of the flesh; from our kindred, when we strive to strip ourselves of all the vices with which we were born, as far as is possible for humans; from our father's house, when we contend to leave the world itself with its prince the devil out of love for heavenly life. For we are all born into the world as sons of the devil because of the guilt of original transgression; but through the grace of regeneration, we belong to the seed of Abraham and become the sons of God, as our Father in heaven says to us, that is, to His Church: "Listen, daughter, and see, and incline your ear, forget your people and your father's house" (Psalms 45:10). Thus it is well that Haran, from which Abraham departed, is interpreted as Wrath. Canaan, to whose land he was invited, is called the Changed or Merchant. Therefore, not only did Abraham and his brother Lot leave Haran to go to the land of Canaan, but all the elect who are born through the laver of regeneration certainly depart from Haran and come to the land of Canaan; and all the chosen, with the wrath of original sin repudiated in the state of their life and having abandoned the habit of vices, apply themselves to virtues and labor in the most blessed commerce of temporal works to attain eternal rewards; they spurn earthly riches to receive heavenly ones; they disdain the joys of human reign to deserve a share in the kingdom of God. For this is the land that the Lord promised to show His followers: because it cannot be discovered by human wisdom how to walk the way of good deeds, but His guidance must be sought in all things, as the Psalmist says: "You held my right hand, you guided me according to your will, and took me with glory" (Psalms 73:23-24). — Commentary on Genesis (Hexaemeron) Jerome : (Chapter 12, Verse 4) Now Abram was seventy-five years old when he departed from Haran. There arises an unsolvable question: for if Terah, the father of Abram, when he was still in the land of the Chaldeans, at seventy years old begot Abram, and afterwards died in Haran at the age of two hundred and five: how is it now mentioned that Abram, after the death of Terah, when departing from Haran, was seventy-five years old? Since from the birth of Abram until the death of his father, it is said that one hundred and thirty-five years passed. Therefore, that tradition of the Hebrews, which we mentioned above, is true: that Thara went out with his sons from the fire of the Chaldeans, and that Abram, surrounded by the Babylonian fire, was liberated by the help of God because he refused to worship it; and from that time, the days of his life, and the reckoning of his age, are considered from when he confessed the Lord, rejecting the idols of the Chaldeans. However, it is possible that because the Scripture left it uncertain, a few years ago Thara set out from Chaldea and came to Haran, where he died. Certainly, after the persecution, he came to Haran and stayed there for a longer time. Therefore, if anyone is opposed to this explanation, they will seek another solution and then rightfully reject what we have said. — Hebrew Questions on Genesis