15 “For You have brought us low in the place of infirmity”: therefore You will exalt us in the place of strength. “And the shadow of death has covered us”. For this mortality of ours is but the “shadow” of death. The true death is condemnation with the devil.
16. “If we have forgotten the Name of our God.” Here is the “understanding” of the “sons of Korah.” “And stretched out our hands to a strange God”. “Shall not God search this out? For He knows the secrets of the heart”. He “knows,” and yet He “searches them out”? If He knows the secrets of the heart, what do the words, “Shall not God search it out,” do there? He “knows” it in Himself; He “searches it out” for our sakes. For it is for this reason God sometimes “searches a thing out;” and speaks of that becoming known to Himself, which He is Himself making known to you. He is speaking of His own work, not of His knowledge. We commonly say, “A gladsome day,” when it is fine. Yet is it the day itself that experiences delight? No: we speak of the day as gladsome, because it fills us with delight. And we speak of a “sullen sky.” Not that there is any such feeling in the clouds, but because men are affected with sullenness at the sight of such an appearance of the skies, it is called sullen for this reason, that it makes us sullen. So also God is said to “know” when He causes us to know. God says to Abraham, “Now I know that you fear God.” Did He then not know it before then? But Abraham did not know himself till then: for it was in that very trial he came to know himself....And God is said to “know” that which He had caused him to know. Did Peter know himself, when he said to the Physician, “I will be with You even unto death?” The Physician had felt his pulse, and knew what was going on within His patient's soul: the patient knew it not. The crisis of trial came; and the Physician approved the correctness of His opinion: the sick man gave up his presumption. Thus God at once “knows” it and “searches it out.” “He knows it already. Why does He 'search it out'?” For your sake: that you may come to know your own self, and may return thanks to Him that made you. “Shall not God search it out?”
17. “For, for Your sake we are killed all the day long: we are counted as sheep for the slaughter”. For you may see a man being put to death; you do not know why he is being put to death. God knows this. The thing in itself is hid. But some one will say to me, “See, he is detained in prison for the name of Christ, he is a confessor for the name of Christ.” Why do not heretics also confess the name of Christ, and yet they do not die for His sake? Nay more; let me say it, in the Catholic Church itself, do you think there either are, or have been wanting persons such as would suffer for the sake of glory among men? Were there no such persons, the Apostle would not say, “Though I give my body to be burned, and have not charity, it profits me nothing.” He knew therefore that there might be some persons, who did this not from “charity,” but out of vainglory. It is therefore hid from us; God alone sees this; we cannot see it. He alone can judge of this, who “knows the secrets of the heart.” “For,” for Your sake “are we killed all the day long; we are counted as sheep for the slaughter.” I have already mentioned that from hence the Apostle Paul had borrowed a text for the encouragement of the Martyrs: that they might not “faint in the tribulations” undergone by them for the name of Christ.
18. “Awake; why sleepest Thou, O Lord?”. Who is addressed, and who is the speaker? Would not he be more correctly said to sleep and slumber, who speaks such words as these? He replies to you, I know what I am saying: I know that “He that keeps Israel does not sleep:” but yet the Martyrs cry, “Awake; why sleepest Thou, O Lord?” O Lord Jesus, You were slain; Thou “slept” in Your Passion; to us You have now “awaked” from sleep. For “we” know that You have now “awaked” again. To what purpose have You awaked and risen again? The Gentiles that persecute us, think You to be dead; do not believe You to have risen again. “Arise Thou” then to them also! “Why sleepest Thou,” though not to us, yet to them? For if they already believed You to have risen again, could they persecute us who believe in You? But why do they persecute? “Destroy, slay so and so, whoever have believed in You, such an one, who died an ill death!” As yet to them “Thou sleepest;” arise to them, that they may perceive that You have “awaked” again; and may be at rest. Lastly, it has come to pass, while the Martyrs die, and say these things; while they sleep, and “awaken” Christ, truly dead in their sleepings, Christ has, in a certain sense, risen again in the Gentiles; i.e. it becomes believed, that He has risen again; so by degrees they themselves, becoming converted to Christ by believing, collected a numerous body: such as the persecutors dreaded; and the persecutions have come to an end. Why? Because Christ, who before was asleep to them, as not believing, has risen in the Gentiles. “Arise, and cast us not off for ever!”
19. “Wherefore hidest Thou Your face:” as if You were not present; as if you had forgotten us? “And forgettest our misery and trouble?”.
20. “For our soul is bowed down to the dust”. Where is it bowed down? “To the dust:” i.e. dust persecutes us. They persecute us, of whom You have said, “The ungodly are not so; but are like the dust, which the wind drives away from the face of the earth.” “Our belly has cleaved to the earth.” He seems to me to have expressed the punishment of the extreme of humiliation, in which, when any one prostrates himself, “his belly cleaves to the earth.” For whosoever is humbled so as to be on his knees, has yet a lower degree of humiliation to which he can come: but he who is so humbled, that his “belly cleaves to the ground,” there is no farther humiliation for him. Should one wish to do still farther, it will, after that point, be not bowing him down, but crushing him. Perhaps then he may have meant this: We are “bowed down very low” in this dust; there is no farther point to which humiliation can go. Humiliation has now reached its highest point: let mercy then come also....
21. “Arise, O Lord, help us”. And indeed, dearly beloved, He has arisen and helped us. For when he awoke (i.e. when He arose again, and became known to the Gentiles) on the cessation of persecutions, even those who had cleaved to the earth were raised up from the earth, and on performing penance, have been restored to Christ's body, feeble and imperfect though they were: so that in them was fulfilled the text, “Your eyes did see my substance yet being imperfect; and in Your book shall they all be written.”
“Arise, O Lord, help us, and redeem us for Your Name's sake;” that is to say, freely; for Your Name's sake, not for the sake of my merits: because You have vouchsafed to do it, not because I am worthy that You should do it unto me. For this very thing, that “we have not forgotten You;” that “our heart has not gone back;” that we “have not stretched out our hands to any strange god;” how should we have been able to achieve, except with Your help? How should we have strength for it, except through Your appealing to us within, exhorting us, and not forsaking us? Whether then we suffer in tribulations, or rejoice in prosperities, redeem Thou us, not for our merits, but for Your Name's sake.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)