4. That the new converts shall strangely increase and multiply. Jerusalem, after she has lost abundance of her children by the sword, famine, and captivity, shall have a new family growing up instead of them, children which she shall have after she has lost the other (v. 20), as Seth, who was appointed another seed instead of Abel, and Job's children, which God blessed him with instead of those that were killed in the ruins of the house. God will repair his church's losses and secure to himself a seed to serve him in it. It is promised to the Jews, after their return, that Jerusalem shall be full of boys and girls playing in the streets, Zech. viii. 5. The church, after it has lost the Jews, who will be cut off by their own infidelity, shall have abundance of children still, more than she had when the Jews belonged to her. See Gal. iv. 27. They shall be so numerous that, (1.) The Children shall complain for want of room; they shall say (and it is a good hearing), "Our numbers increase so fast that the place is too strait for us;" as the sons of the prophets complained, 2 Kings vi. 1. But, strait as the place is, still more shall desire to be admitted, and the church shall gladly admit them, and the inconvenient straitness of the place shall be no hindrance to either; for it will be found, whatever we think, that even when the poor and the maimed, the halt and the blind, are brought in, yet still there is room, room enough for those that are in and room for more, Luke xiv. 21, 22. (2.) The mother shall stand amazed at the increase of her family, v. 21. She shall say, Who has begotten me these? and, Who has brought up these? They come to her with all the duty, affection, and submission of children; and yet she never bore any pain for them, nor took any pains with them, but has them ready reared to her hand. This gives her a pleasing surprise, and she cannot but be astonished at it, considering what her condition had been very lately and very long. The Jewish nation had left her children; they were cut off. She had been desolate, without ark, and altar, and temple-service, those tokens of God's espousals to them; nay, she had been a captive, and continually removing to and fro, in an unsettled condition, and not likely to bring up children either for God or herself. She was left alone in obscurity (this is Zion whom no man seeks after), left in all the solitude and sorrow of a widowed state. How then came she to be thus replenished? See here, [1.] That the church is not perpetually visible, but there are times when it is desolate, and left alone, and made few in number. [2.] That yet on the other hand its desolations shall not be perpetual, nor will it be found too hard for God to repair them, and out of stones to raise up children unto Abraham. [3.] That sometimes this is done in a very surprising way, as when a nation is born at once, ch. lxvi. 8.