By saying that his soul was remote from peace, he means that no good remained; for by peace, as it is well known, the Hebrews understood every kind of prosperity. And he explains himself by another clause, that, he had forgotten every good; and this forgetfulness ought to be understood, so to speak, as real or entire; for if there had been any reason for rejoicing, it would not have been forgotten; for all are naturally pleased with what is pleasant, nay, they with avidity seek what delights them. It would then be contrary to nature to forget things good and pleasant, to us. But the Prophet means here a privation. Hence the forgetfulness of which he speaks is nothing else but alienation from everything good, as though he had said (as the previous clause shews) that he was removed from every hope of peace. But the expression is much more emphatical, when he says, that his soul was far removed from peace. By soul he does not mean himself only, (for that would be frigid,) but he understands by it all things connected with him, as though he had said, "Wherever I look around me, I find no peace, and no hope appears to me." Hence it was, that all the faculties of his soul were far removed from all experience of good things. It follows, --

Prosperity - literally, as in the margin, i. e. I forgot what good was, I lost the very idea of what it meant.

Those hast removed my soul - Prosperity is at such an utter distance from me, that it is impossible I should ever reach it; and as to happiness, I have forgotten whether I have ever tasted of it.

And thou hast removed my soul far off from peace,.... From the time the city was besieged by the Chaldeans, and now the people was carried captive; who could have no true peace, being in a foreign land, in an enemy's country, and out of their own, and far from the place of divine worship; nor could the prophet have any peace of soul, in the consideration of these things, the city, temple, and nation, being desolate, though he himself was not in captivity.
I forgat prosperity; or "good" (q); he had been so long from the enjoyment of it, that he had lost the idea of it, and was thoughtless about it, never expecting to see it any more.
(q) "bonorum", V. L. "boni", Pagninus, Montanus, Cocceius, Junius & Tremellius, Piscator, Michaelis.

Not only present, but all hope of future prosperity is removed; so much so, that I am as one who never was prosperous ("I forgat prosperity").