They shall perish - That is, the heavens and the earth. They shall pass away; or they shall be destroyed. Probably no more is meant by the phrase here, than that important changes will take place in them, or than that they will change their form. Still it is not possible to foresee what changes may yet take place in the heavenly bodies, or to say that the present universe may not at some period be destroyed, and be succeeded by another creation still more magnificent. He that created the universe by a word, can destroy it by a word and he that formed the present frame of nature can cause it to be succeeded by another not less wonderful and glorious. The Scriptures seem to hold out the idea that the present frame of the universe shall be destroyed; see 2-Peter 3:10-13; Matthew 24:35. "But thou remainest." Thou shalt not die or be destroyed. What a sublime thought! The idea is, that though the heavens and earth should suddenly disappear, or though they should gradually wear out and become extinct, yet there is one infinite being who remains unaffected and unchanged.
Nothing can reach or disturb him. All these changes shall take place under his direction, and by his command; see Revelation 20:11. Let us not be alarmed then at any revolution. Let us not fear though we should see the heavens rolled up as a scroll, and the stars falling from their places. God, the Creator and the Redeemer, presides over all. He is unchanged. He ever lives; and though the universe should pass away, it will be only at his bidding, and under his direction. "And they all shall wax old." Shall "grow" or become old. The word "wax" is an Old Saxon word, meaning to grow, or increase, or become. The heavens here are compared to a garment, meaning that as that grows old and decays, so it will be with the heavens and the earth. The language is evidently figurative; and yet who can tell how much literal truth there may be couched under it? Is it absurd to suppose that that sun which daily sends forth so many countless millions of beams of light over the universe, may in a course of ages become diminished in its splendor, and shine with feeble lustre? Can there be constant exhaustion, a constant burning like that, and yet no tendency to decay at some far distant period? Not unless the material for its splendor shall be supplied from the boundless resources of the Great Source of Light - God; and when he shall choose to withhold it, even that glorious sun must be dimmed of its splendor, and shine with enfeebled beams.

They shall perish - Permanently fixed as they seem to be, a time shall come when they shall be dissolved, and afterward new heavens and a new earth be formed, in which righteousness alone shall dwell. See 2-Peter 3:10-13.
Shall wax old as doth a garment - As a garment by long using becomes unfit to be longer used, so shall all visible things; they shall wear old, and wear out; and hence the necessity of their being renewed. It is remarkable that our word world is a contraction of wear old; a term by which our ancestors expressed the sentiment contained in this verse. That the word was thus compounded, and that it had this sense in our language, may be proved from the most competent and indisputable witnesses. It was formerly written weorold, and wereld. This etymology is finely alluded to by our excellent poet, Spencer, when describing the primitive age of innocence, succeeded by the age of depravity: -
"The lion there did with the lambe consort,
And eke the dove sat by the faulcon's side;
Ne each of other feared fraude or tort,
But did in safe security abide,
Withouten perill of the stronger pride:
But when the World woxe old, it woxe warre old,
Whereof it hight, and having shortly tride
The trains of wit, in wickednesse woxe bold,
And dared of all sinnes, the secrets to unfold."
Even the heathen poets are full of such allusions. See Horace, Carm. lib. iii., od. 6; Virgil, Aen. viii., ver. 324.
Thou remainest - Instead of διαμένεις, some good MSS. read διαμενεῖς, the first, without the circumflex, being the present tense of the indicative mood; the latter, with the circumflex, being the future - thou shalt remain. The difference between these two readings is of little importance.

They shall perish,.... That is, the heavens and the earth; not as to the substance of them, but as to the quality of them; the present form and fashion of them shall pass away; the curse will be removed from them, and they will be renewed and purified, but the substance of them will continue; otherwise there would be no place, either for the righteous or the wicked,
But thou remainest; without any change or alteration, neither in his natures, divine or human, as God or man, nor in his office as Mediator; as a priest, he has an unchangeable priesthood, and ever lives to make intercession; as a King, his kingdom is an everlasting one, and of it there will be no end; and as a prophet, he will be the everlasting light, of his people.
They all shall wax old as doth a garment; garments in time wax old, and lose their beauty and usefulness, unless when a miracle is wrought, as in the case of the children of Israel in the wilderness. Now the heavens, and the light thereof, are as a garment and a curtain, Psalm 104:2 and these, together with the earth, will in time come to their end of usefulness, in the present form of them; see Isaiah 51:6.

They--The earth and the heavens in their present state and form "shall perish" (Hebrews 12:26-27; 2-Peter 3:13). "Perish" does not mean annihilation; just as it did not mean so in the case of "the world that being overflowed with water, perished" under Noah (2-Peter 3:6). The covenant of the possession of the earth was renewed with Noah and his seed on the renovated earth. So it shall be after the perishing by fire (2-Peter 3:12-13).
remainest--through (so the Greek) all changes.
as . . . a garment-- (Isaiah 51:6).