Augustine of Hippo

What did the prophet Isaiah mean when he announced that a mountain would be prepared on the summits of the mountains, to which all peoples were going to come? The law and the Word of God was going to proceed from Zion and Jerusalem to all nations, not from Mount Sinai to one nation. This we see most evidently fulfilled in Christ and the Christians. A little later the prophet says, "O house of Jacob, come and let us walk in the light of the Lord." Here, you [the Jews] will surely say your usual piece: "We are the house of Jacob," but listen a moment to what follows, and when you have said what you want to say, hear what you do not want to hear. The prophet continues, "For he has cast off his people, the house of Israel." Here say, "We are the house of Israel"; here acknowledge yourselves and forgive us for reminding you of these facts.