Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
Isaiah Chapter 6
But it was in the counsels of God that His presence should be established in glory in the midst of His people, and this will be accomplished in Christ at the end of the age. Hence the testimony of the progress of the judgments is interrupted after the first general statement, and in chapter 6 the prophet sees this glory. Yet its first effect is judicial, and operates to blind and condemn them. The previous judgment (chap. 5) had been in respect of the breaking of the law and the despising of the word of the Holy One of Israel. But with enmity against Christ and His rejection comes judicial blindness and the separation of a remnant. That it is the glory of Christ is taught us in chapter 12 of John's Gospel. The prophet feels at once the incompatibility of the people's condition with the manifestation of this glory. Unclean lips cannot celebrate it. But a live coal from the altar cleanses his own lips, and he consecrates himself to Jehovah's message; and to that which concerns the glory of Christ. The heart of the people is made fat until there is entire desolation. Nevertheless there shall be a remnant, a holy seed, which shall be like the sap of a tree that has lost its leaves. [See Note #1]
We have then in these last chapters the judgment of the people under two aspects: first, that of God's government (in this point of view the people, being altogether guilty, are given up to the Gentiles); secondly, in view of the glory of Jehovah's presence at His coming according to His purposes of grace (for this the people were unfit). But here, as the purposes of God were in question, there is a remnant according to election in whom the glory shall be re-established. This distinction must be made when the government of God and His outward dealings are in question. In chapter 5, which speaks of the former character of judgment, there is no remnant. It is simply the public and complete judgment of the nation; for as to this all rested on their responsibility. In the Gospels this is looking for fruit; Christ might dig about it and dung it, but this was looking for fruit. Hence it is cursed and never to bear fruit. That is Israel (man) under the first covenant. In chapter 6 God acts within, in His own relationship with the people. Hence we find a remnant and the assured re-establishment of the people; for the gifts and calling of God are without repentance. Here also we find Christ. God could not cast off His people for ever, and the prophetic faith is found which says, How long? as elsewhere it is said, There is none to say, How long? For when the Son of man cometh, shall He find faith on earth?
Note #1
A more exact translation throws much light on this prophecy. Nevertheless there shall still be in it a tenth, and it shall return and shall be to be consumed, as the oak and the teil tree, which being cut down have still the trunk [or the rooted stump]; thus the holy seed shall be their stock" (Isa 1:9). That is, the remnant itself will undergo Judgment and consumption at the time of their return; but there shall be a holy seed, from which life will spring as from a tree cut down.