And the LORD appeared unto him by the oaks of Mamre: and he sat in the tent door in the heat of the day;
Read Chapter 18
Ambrose of Milan
Abraham, who was glad to receive strangers, faithful to God and tireless in his service and prompt in fulfilling his duty, saw the Trinity typified. He added religious devotion to hospitality, for although he beheld three, he adored one, and, while keeping a distinction of the persons, yet he called one Lord, thus giving honor to the three but signifying one power. For not knowledge but grace spoke in him. And he believed better what he had not learned than we who have been taught. No one had falsified the type of truth, and therefore he saw three but worshiped their unity. He brought out three measures of meal but slaughtered one calf, believing one sacrifice was sufficient, but a threefold offering; one victim, but a threefold gift. On His Brother, Satyrus
God appeared again to Abraham at the oak of Mamre in three men, who it is not to be doubted were angels, although some think that one of them was Christ and assert that he was visible before he put on flesh. Now it belongs to the divine power and invisible, incorporeal and incommunicable nature, without changing itself at all, to appear even to mortals, not by what it is but by what is subject to it. And what is not subject to it? Yet if they try to establish that one of these three was Christ by the fact that although he saw three, he addressed the Lord in the singular, as it is written, “He lifted up his eyes and looked, and behold, three men stood in front of him. When he saw them, he ran from the tent door to meet them, and bowed himself to the earth and said, ‘My lord, if I have found favor in your sight.’ ” Why do they not refer also to this, that when two of them came to destroy the Sodomites, while Abraham still spoke to one, calling him Lord and interceding that he would not d...
Now where did this happen? “Near the holmoak of Mamre,” which in Latin is interpreted as “vision” or “discernment.” Do you see what kind of a place it is in which the Lord can have a feast? The vision and discernment of Abraham delighted him; he was clean of heart, so that he could see God. Therefore in such a place and in such a heart the Lord can have his feast. Of this vision our Lord spoke to the Jews in the Gospel when he said, “Abraham rejoiced that he was to see my day. He saw it and was glad.” He saw my day, he says, because he recognized the mystery of the Trinity. He saw the Father as day, the Son as day, the Holy Spirit as day, and in these three one day. Thus the Father is God, the Son is God, the Holy Spirit is God, and these three are one God. For individually each person is complete God, and all three together are one God. Moreover, because of the unity of substance, in those three measures of flour the Father, Son and Holy Spirit are not unfittingly understood. However,...
Thus the Lord God is said to have appeared as a common man to Abraham while he was seated by the oak of Mamre. But [Abraham] immediately fell down, although he saw a man with his eyes, and worshiped him as God, besought him as Lord and confessed that he was not ignorant as to who he was, using these very words, “O Lord, judge of all the earth, will you not judge righteously?” For if it should be unreasonable to suppose that the unbegotten and immutable substance of God the Almighty was changed into the form of man and, in turn, that the eyes of the beholders were deceived by the phantasm of something created and that such things were falsely invented by Scripture, who else could be proclaimed God and the Lord who judges all the earth and judges righteously, appearing in the shape of a man—if it be not proper to call him the first cause of all things—than his preexistent Word alone? Ecclesiastical History.