Athanasius of Alexandria : By means of righteousness we come into God's presence, as Moses did when he entered the thick cloud where God was. On the other hand, by the practice of evil a person leaves the presence of the Lord. For example, Cain, when he killed his brother, left the Lord's presence as far as his will was concerned. — FESTAL LETTERS 10 Bede : And Cain went out from the presence of the Lord, that is, from the inner parts of those dwellings in which he had been living with his parents until then, and was often accustomed to see Him in angelic form. — Commentary on Genesis (Hexaemeron) Bede : He dwelled in the land as a fugitive to the east of Eden. Eden is interpreted as pleasure or delight, by which name paradise is designated, about which it is said above: "And the Lord God planted a garden of pleasure from the beginning," which ancient interpreters have thus translated: "And the Lord God planted a garden in Eden to the east," from which it is understood that paradise is established to the eastern region of the world. Therefore, Cain dwelled not to the eastern region of paradise, otherwise he would dwell beyond this world, but in the eastern parts of the world, where paradise is nearby, although inaccessible and unknown to mortals. All things that are said literally about the justice or martyrdom of Abel, and about the depravity and condemnation of Cain, mystically testify to the passion of the Lord, the incarnation and persecution, and the destruction of the Jews. For the Lord says to those same Jews: "If you believed Moses, you would perhaps believe me as well; for he wrote about me" (John 5:46). Thus Cain was the firstborn, Abel the second. The people of the Jews were God's first possession, as He Himself said to Moses, "Israel is my son, my firstborn" (Exodus 4:22); the second is the people of the gentiles, for whom especially the Son of God deemed it worthy to be born in the flesh and to die. Abel was a shepherd of sheep, and the Lord said: "I am the good shepherd" (John 10:14). But Cain was a farmer, because the people of the Jews were involved in earthly and temporal affairs, either pursuing these alone or serving the Lord with these in mind, as they carnally understood those things which the prophets spoke mystically about the heavenly promise, saying: "If you are willing and obedient, you shall eat the good of the land" (Isaiah 1:19). — Commentary on Genesis (Hexaemeron) Bede : And Cain went out from the presence of the Lord and dwelt in the land of Nod to the east of Eden. By the presence of the Lord is usually understood the recognition by which He manifests and is known. Therefore, deservedly, the people who have withdrawn from the grace of divine recognition are said to dwell on earth. For they cannot say with the elect, "Our citizenship is in heaven, from where we also eagerly wait for the Savior, the Lord Jesus Christ" (Philippians 3:20). The Septuagint interpreters translated this passage thus: "Now Cain went out from the presence of the Lord God and dwelt in the land of Naid opposite Eden." Naid, however, is translated as "fugitive," or as we find in the book of Hebrew names, "unstable motion and fluctuation," which some, including Josephus, agree to be the place where Cain dwelt. Furthermore, our interpreter understood not the name of a place, but the significance of the thing itself; because Cain would be always unstable and fluctuating and of uncertain abodes. How much this matches the present state of the Jews, the whole world is a witness. They are also rightly said to dwell opposite Eden. For Eden signifies pleasure or delight: because indeed that faithless people, as much as they turn away from the knowledge of truth and entangle themselves in earthly affairs, so much they live a life contrary to heavenly delights; and because they only thirst for temporal joys, they are adversaries with the dry throats of their hearts to the torrent of divine pleasure by which the righteous are refreshed. — Commentary on Genesis (Hexaemeron) Clement of Alexandria : The Scripture makes good sense: "Cain left God's presence and went to live in the land of Nod, opposite Eden." Nod means "disturbance," Eden, "the good life." The good life from which the transgressor was expelled consisted in faith, knowledge, peace. Those wise in their own eyes … are happy to transfer to the disturbance of a tossing sea. They drop from the knowledge of the One who knows no birth to the realm of birth and death. Their opinions are constantly changing. — The Stromata Book 2 Ephrem the Syrian : After Cain received the punishment and the sign had been added to it … Moses said that "Cain went away from the presence of the Lord and dwelt in the land of Nod, east of Eden." Cain, therefore, separated himself from his parents and his kin because he saw that they would not intermarry with him. — COMMENTARY ON Genesis 3.11.1 Ephrem the Syrian : The land of Nod is so called because it was the land in which Cain wandered about in fear and trembling. But the land also received a second curse when God said, "When you till the earth it shall no longer yield to you its strength." — COMMENTARY ON Genesis 3.11.1 Ephrem the Syrian : There the families of the two brothers had separated: Cain went off by himself and lived in the land of Nod, a place lower still than that of Seth and Enosh; but those who lived on higher ground, who were called "the children of God," left their own region and came down to take wives from the daughters of Cain down below. — HYMNS ON PARADISE 1.11 Jerome : (Verse 16.) And he dwelt in the land of Naid. Which the Septuagint translated as Naid, but in Hebrew it is called Nod, meaning 'shaking', that is, unstable and fluctuating, with an uncertain dwelling place. Therefore, it is not the land of Naid, as our common people think, but the divine sentence is fulfilled, that he wandered and fled here and there. — Hebrew Questions on Genesis