Isaiah 2:3

(Verse 3.) And they shall say: Come, let us go up to the mountain of the Lord, and to the house of the God of Jacob: and he will teach us his ways, and we will walk in his paths. The nations and peoples, not content with their own salvation, will encourage one another and say: Come, let us go up to the mountain of the Lord and to the house of the God of Jacob. Concerning these, as we have said before, it is the mountain of the Lord that is prepared and the house of the Lord that is established upon the top of the mountains. But the house of the Lord is called the house of the God of Jacob, so that we may receive the Old Testament and not, like the Manicheans, seek another house outside the house of the God of Jacob. But when we are in the house of the God of Jacob, then he will teach us his ways, by which we will walk towards him, and we will walk in his paths, which others have also walked. Finally, Jesus, ascending the mountain, taught his disciples the eight beatitudes, and other things which are included in the Gospel discourse (Luke VI). First, the ways of the Lord must be descended; and afterwards, we must walk in his paths. For out of Zion shall go forth the law, and the word of the Lord from Jerusalem. Many nations and peoples will come together and say: Come, let us go up to the mountain of the Lord, and so on. For out of Zion shall go forth the law, and the word of the Lord from Jerusalem, not from Sinai, or from the wilderness, or from Mount Horeb, but from Mount Zion, where Jerusalem is built, and from Jerusalem, where the Temple and the worship of God are. We read that often the Lord taught in the Temple (Matthew 13), and that it was not fitting for a prophet to die outside of Jerusalem, and that both the word and the law are named together. The rulers are commanded to hear the word, and the people to perceive the law with their ears. […]

The first law, the Old Testament, had come out of Mount Sinai by the lips of Moses; but it was foretold of the law Christ came to give: "The law shall come forth from Zion, and the word of the Lord from Jerusalem." This explains why Christ ordered repentance to be preached in his name among all peoples but beginning in Jerusalem.

The order of conversion was that the gentiles were converted through the calling of those who were from the Jews. And therefore he sets out three things: first, those who call, second, the calling, where it says, "come," third, the reason for this order, where …

It was opportune that the preaching of repentance and the forgiveness of sins through confession of Christ's name should have started from Jerusalem. Where the splendor of his teaching and virtues, where the triumph of his passion, where the joy of his resurrection and ascension …

The law - The new law, the doctrine of the gospel, which is frequently called a law, because it hath the nature and power of a law, obliging us no less to the belief and practice of it, than the old law did.

The means by which this shall be brought about: Out of Zion shall go forth the law, the New-Testament law, the law of Christ, as of old the law of Moses from Mount Sinai, even the word of the Lord from Jerusalem. The gospel is a law, a law of faith; it is the word of the Lord; it went forth from Zion, where the temple was built, and from Jerusalem.

And many people shall go - This denotes a prevalent “desire” to turn to the true God, and embrace the true religion. It is remarkable that it speaks of an inclination among them to “seek” God, as if they were satisfied of the folly and danger of their ways, and felt the necessity of obtaining a better religion. In many cases this has occurred. Thus, in modern times, the people of the Sandwich Islands threw away their gods and remained without any religion, as if waiting for the message of life.

If the curse foretold against Israel has been literally fulfilled, so shall the promised blessing be literal. We Gentiles must not, while giving them the curse, deny them their peculiar blessing by spiritualizing it.

To the house - The conjunction ו vau is added by nineteen of Kennicott’s, thirteen of De Rossi’s MSS., one of my own, and two editions, the Septuagint, Syriac, Vulgate, Arabic, and some copies of the Targum; And to the house. It makes the sentence more emphatic. He will teach us of his ways - Unless God grant a revelation of his will, what can we know? We will walk in his paths - Unless we purpose to walk in the light, of what use can that light be to us? For out of Zion shall go forth the law - In the house of God, and in his ordinances only can we expect to hear the pure doctrines of revelation preached. 1. God alone can give a revelation of his own will. 2. We must use the proper means in order to know this will. 3. We should know it in order to do it. 4. We should do it in order to profit by it. 5. He who will not walk in the light when God vouchsafes it, shall be shut up in everlasting darkness. 6. Every man should help his neighbor to attain that light, life, and felicity: “Come ye, and let us walk in the light of the Lord.”