(3) When thou didst terrible things . . .—The latter clause, “thou camest down . . .” is supposed by some critics to be an accidental repetition from Isaiah 64:1. By others it is taken as an intentional repetition, emphasising the previous assertion, after the manner of Hebrew poetry. The latter view seems to have most in its favour.

Isaiah 64:3-4. When thou didst terrible things — This may relate to what he did first in Egypt, and afterward in the wilderness; which we looked not for — Such things as we could not have expected; the mountains flowed down — See Exodus 19:18; Deuteronomy 32:22; Psalm 18:7, with the notes. But Lowth proposes another interpretation, which he thinks agrees better with what follows, namely, When thou shalt do terrible and unexpected things, when thou shalt come down, (and visibly interpose for the deliverance of thy people,) the mountains shall melt at thy presence. For since the beginning of the world, &c. — “The methods of thy dispensations, whereby thou wilt fulfil thy promises made to thy people, are beyond any thing we can think or conceive.” Bishop Lowth translates this verse, more agreeably both to the Hebrew and the LXX., thus: For “never have men heard, nor perceived, by the ear; nor hath eye seen a God besides thee, who doeth such things for those, that trust in him.” Some of the Jewish doctors have understood this passage of the blessings belonging to the days of the Messiah; and to them the apostle applies it, 1 Corinthians 2:9. Others extend it to the glories of the world to come. Of both these it may be truly said, that from the beginning of the world men have not, either by hearing or seeing; or, as the apostle adds, by any reasonings or conceptions of their own minds, come to the full knowledge of them. None have seen or heard, or can understand, but God himself; and so far as he has been, and is, pleased to reveal it by his Spirit, what the provision is, which is made for the present and future felicity of holy souls; or, as our translation here expresses it, of those that wait for him, namely, in the way of duty; that sincerely and earnestly desire, and live in the daily and ardent expectation of, the salvation he hath promised them. The apostle has it, that love him; to show that as none can wait for him who do not love him, so all that love him will wait for him.

64:1-5 They desire that God would manifest himself to them and for them, so that all may see it. This is applicable to the second coming of Christ, when the Lord himself shall descend from heaven. They plead what God had used to do, and had declared his gracious purpose to do, for his people. They need not fear being disappointed of it, for it is sure; or disappointed in it, for it is sufficient. The happiness of his people is bound up in what God has designed for them, and is preparing for them, and preparing them for; what he has done or will do. Can we believe this, and then think any thing too great to expect from his truth, power, and love? It is spiritual and cannot be comprehended by human understanding. It is ever ready. See what communion there is between a gracious God and a gracious soul. We must make conscience of doing our duty in every thing the Lord our God requires. Thou meetest him; this speaks his freeness and forwardness in doing them good. Though God has been angry with us for our sins, and justly, yet his anger has soon ended; but in his favour is life, which goes on and continues, and on that we depend for our salvation.When thou didst terrible things - In delivering the people from Egypt, and in conducting them to the promised land.

Which we looked not for - Which we had never before witnessed, and which we had no right to expect.

Thou camest down - As on Mount Sinai.

The mountains flowed down - (See the notes above). The reference is to the manifestations of smoke and fire when Yahweh descended on Mount Sinai (see Exodus 19:18).

3. When—Supply from Isa 64:2, "As when."

terrible things—(Ps 65:5).

we looked not for—far exceeding the expectation of any of our nation; unparalleled before (Ex 34:10; Ps 68:8).

camest down—on Mount Sinai.

mountains flowed—Repeated from Isa 64:1; they pray God to do the very same things for Israel now as in former ages. Gesenius, instead of "flowed" here, and "flow" in Isa 64:1, translates from a different Hebrew root, "quake … quaked"; but "fire" melts and causes to flow, rather than to quake (Isa 64:2).

When thou didst terrible things: this may relate to what he did among the Egyptians, though it be not recorded, and afterward in the wilderness.

Which we looked not for, viz. our forefathers, of whose race we are; before we expected them; or such things as we could never expect.

The mountains flowed down: q.d. Seeing thou hast made the mountains thus to melt, thou canst do the same again. This may allude either,

1. To those showers of rain that fell with that terrible thunder and lightning, and so ran violently down those mountains, and the adjacent, as is usual in such tempests. Or rather,

2. The running along of the fire upon the ground, Exodus 9:23,24. It is possible it may allude to those mountains that do cast forth sulphurous matter, running down into the valleys and sea, like melted streams of fire. And kings, princes, and potentates may also metaphorically be understood by these mountains.

When thou didst terrible things, which we looked not for, thou camest down,.... Referring to the wonderful things God did in Egypt, at the Red sea, and in the wilderness, and particularly at Mount Sinai, things that were unexpected, and not looked for; then the Lord came down, and made visible displays of his power and presence, especially on Mount Sinai; see Exodus 19:18,

the mountains flowed down at thy presence; not Sinai only, but others also; Kimchi says Seir and Paran; Judges 5:4.

When thou didst terrible things which we looked not for, thou camest down, the mountains flowed down at thy presence.