God is of an eternal duration

 God is of an eternal duration. The eternity of God is the foundation of the stability of the covenant, the great comfort of a Christian. The design of God in Scripture is, to set forth his dealing with men in the way of a covenant. The priority of God before all things begins the Bible: “In the beginning God created” (Gen. i. 1). His covenant can have no foundation, but in his duration before and after the world:539 and Moses here mentions his eternity, not only with respect to the essence of God, but to his federal providence; as he is the dwelling‑place of his people in all generations. The duration of God forever is more spoken of in Scripture than his eternity, à parte ante, though that is the foundation of all the comfort we can take from his immortality: if he had a beginning, he might have an end, and so all our happiness, hope and being would expire with him; but the Scripture sometimes takes notice of his being without beginning, as well as without end: “Thou art from everlasting” (Ps. xciii. 2); “Blessed be God from everlasting to everlasting” (Ps. xli. 13); “I was set up from everlasting” (Prov. viii. 23): if his wisdom were from everlasting, himself was from everlasting: whether we understand it of Christ the Son of God, or of the essential wisdom of God, it is all one to the present purpose. The wisdom of God supposeth the essence of God, as habits in creatures suppose the being of some power or faculty as their subject. The wisdom of God supposeth mind and understanding, essence and substance. The notion of eternity is difficult; as Austin said of time,540 if no man will ask me the question, what time is, I know well enough what it is; but if any ask me what it is, I know not how to explain it; so may I say of eternity; it is easy in the word pronounced, but hardly understood, and more hardly expressed; it is better expressed by negative than positive words. Though we cannot comprehend eternity, yet we may comprehend that there is an eternity; as, though we cannot comprehend the essence of God what he is, yet we may comprehend that he is; we may understand the notion of his existence, though we cannot understand the infiniteness of his nature; yet we may better understand eternity than infiniteness; we can better conceive a time with the addition of numberless days and years, than imagine a Being without bounds; whence the apostle joins his eternity with his power; “His eternal power and Godhead” (Rom. i. 20); because, next to the power of God, apprehended in the creature, we come necessarily by reasoning, to acknowledge the eternity of God. He that hath an incomprehensible power must needs have an eternity of nature; his power is most sensible in the creatures to the eye of man, and his eternity easily from thence deducible by the reason of man. Eternity is a perpetual duration, which hath neither beginning nor end; time hath both. Those things we say are in time that have beginning, grow up by degrees, have succession of parts; eternity is contrary to time, and is therefore a permanent and immutable state; a perfect possession of life without any variation; it comprehends in itself all years, all ages, all periods of ages; it never begins; it endures after every duration of time, and never ceaseth; it doth as much outrun time, as it went before the beginning of it: time supposeth something before it; but there can be nothing before eternity; it were not then eternity. Time hath a continual succession; the former time passeth away and another succeeds: the last year is not this year, nor this year the next. We must conceive of eternity contrary to the notion of time; as the nature of time consists in the succession of parts, so the nature of eternity in an infinite immutable duration. Eternity and time differ as the sea and rivers; the sea never changes place, and is always one water; but the rivers glide along, and are swallowed up in the sea; so is time by eternity.541