Praised be Jesus and Mary, now and forever.
First a word about the gospel and then I'll mainly talk about the first reading.  So these fruits of trees have been interpreted in various ways, but the context here with Jesus telling His disciples to beware of false prophets seems to support the interpretation that the trees are our teachings, our systems of doctrine. And so when a good system of doctrine or good principles is put into practice, it will bear good fruit. And when a bad system of principles, a heretical doctrine, is put into practice, it cannot bear good fruit. No, it cannot make you a good person to follow bad principles.   But you may profess good principles, true principles, and yet not follow them in practice. And then in practice, you know, but it's what you show by your practice that your principles are, that will determine whether or not you become good fruit or bad fruit.  So we turn our attention now to the first reading. Now to the first reading, which narrates events that took place about ten years after God called Abram to leave his father's house. God's words at the beginning of the reading are a response to what happened just before this passage, so it's helpful to summarize those events. Lot was living in Sodom because his herds and Abram's had become too large for them to both remain in the same area, and the land around Sodom was good. So he chose that as the area in which he was going to live.
 Then a war came. An alliance of four kings attacked the five cities of the plain, one of which was Sodom. Lot's side lost the battle and he was taken captive. So Abraham went to rescue him, taking with him a force of 318 men from his household. This gives some idea of how many people Abraham had working for him at this point. Abram was successful and freed not only Lot but also the other captives and the possessions that the attackers had looted.
 When he returned Melchizedek blessed him as we heard part of that passage on Sunday and the king of Salem wanted to give him some of the looted possessions as a reward for bringing them back but Abram declined he didn't want to be rewarded or made rich by a human being and this is why God said "Fear not, Abram, I am your shield I will make your reward very great."  Abram had just faced great danger, attacking a force that had already defeated a larger army than the force that Abram had. Furthermore, the king of Sodom might be offended by the fact that Abram refused the reward that he offered. But he need not fear, for the Lord is His shield. Furthermore, He was right to decline the reward offered by the king of Sodom. For the Lord says, "I will make your reward very great."  In the West, at least by the Middle Ages, God's words were understood a little differently, which we can translate this other understanding this way. "Fear not, Abram, I am your shield, your very great reward." That is, God was promising Abram the beatific vision, in which He Himself would be Abram's reward. Whether or not this is what God meant here, it is quite true.
 In this very passage, Abram believed the Lord, and He counted it to him as righteousness. St. Paul quotes this and observes that Abraham was justified by faith. Justification means that he had sanctifying grace, and that means that heaven was his inheritance, although he could not receive it until Christ completed the work of redemption. So God was indeed his very great reward. But Abram was concerned about the fact that he had no children.
 He traveled throughout the land of Canaan, and God told him, "To your descendants, I will give this land." But it had been 10 years since he left for Canaan, and now he's 85 and still has no children. He's thinking about adopting his chief servant as a son so that he can pass the inheritance to him. Maybe God was talking about descendants in that sense, descendants by means of adoption. But God responds, "No, that one shall not be your heir. Your own issue shall be your heir."  The Lord then took him outside, so this vision must have begun in Abram's tent during the night. Then God said, "Look up at the sky and count the stars if you can. Just so shall your descendants be." There were no city lights back then to limit our vision of the stars, and so tens of thousands of stars would have been visible. Abram believed God, which was no small act of faith.
 Naturally speaking, he had no hope of having any descendants. His wife was sterile and past the childbearing age, and he himself was not a young man. The comparison to the stars shows that his descendants will be countless, but the fathers of the Church understand it to mean something more. St. Augustine points out that God already told Abram that his descendants would be like the dust of the earth. Since there are far more grains of dust than there are visible stars, the comparison to the stars wouldn't be saying less than God had already said, unless it meant something more than just the quantity of descendants.
 As the stars are in the heavens, so Abram's descendants will be in heaven, because he is our father in faith. Remember that this comparison was made at the same time that Abraham was justified by faith. Then God does still more. He makes a covenant with Abram to assure him that he will possess the land of Canaan.
 This was the first time that God made a covenant with Abram. That may be why it's described in such detail. In the ancient Near East, covenants were made by offering sacrifice and taking oaths. By means of the sacrifices and oaths, a divinity or divinities was invoked to ensure faithfulness to the covenant. Faithfulness will be rewarded by blessings and unfaithfulness will be punished by curses. The symbolism of the animals split in half is to say, "May I suffer what these animals did if I violate this covenant."  The fathers of the Church see a further significance in the specific animals chosen and what happens to them. Keep in mind that this context or that the context regards Abram's descendants. In fact, in a part of the reading, or in a passage that the reading skipped, God tells Abram that his descendants will go live in a foreign land, be afflicted there for 400 years, and finally be delivered and returned to Canaan. This is a prophecy of the slavery of the Israelites in Egypt and their exodus afterwards. So the fathers of the Church see the animals as representing Abram's descendants.
 The three animals that are divided represent the Israelites who are his natural descendants. St. Augustine suggests this interpretation. The heifer was a sign that the people should be put under the law. The she-goat that the people was to become sinful, the ram that they should reign. The birds that were not divided signify spiritual people who are not divided, but love God with their whole heart, soul, and mind. Such people are Abram's spiritual descendants, whether or not they are among his natural descendants. Those who are carnal, on the other hand, will be judged in the way the fire passing between the divided animals signified.
Remember that the divided animals signify what will happen to those who do not observe the covenant.  St. Augustine explains that the sunset signifies the end of the world. So the end of the day corresponds to the end of the world. And the fire that passes between the divided animals signifies the fire of hell. And thus, the vision is terrifying to Abraham.  Let us rather love God with an undivided heart. We love Him with our whole heart, soul, mind, soul, and strength, so as to be descendants of Abraham, worthy of a place in heaven.
Praised be Jesus and Mary, now and forever.