16 “If I said, I shall declare thus; behold, the generation of Your sons I have reprobated”: that is, I will teach thus. How will you teach? That there is no knowledge in the Most High, that God does not know? Will you propound this opinion, that without cause men live justly who do live justly; that a just man has lost his service, because God does more show favour to evil men, or else He does care for no one? Will you tell this, declare this? He does restrain himself by an authority repressing him. What authority? A man wishes some time to break out in this sentiment: but he is recalled by the Scriptures directing us always to live well, saying, that God does care for things human, that He makes a distinction between a godly man and an ungodly man. Therefore this man also wishing to put forth this sentiment, does recollect himself. And what says he? “I have reprobated the generation of Your sons.” If I shall declare thus, the generation of just men I shall reprobate. As also some copies have it, “Behold, the generation of your sons with which I have been in concert:” that is, with which consisting of Your sons I have been in concert; that is, with which I have agreed, to which I have been conformed: I have been out of time with all, if so I teach. For he does sing in concert who gives the tune together; but he that gives not the tune together does not sing in concert. Am I to say something different from that which Abraham said, from that which Isaac said, from that which Jacob said, from that which the Prophets said? For all they said that God does care for things human, am I to say that He cares not? Is there greater wisdom in me than in them? Greater understanding in me than in them? A most wholesome authority has called back his thought from ungodliness. And what follows? That he might not reprobate, he did what? “And I undertook to know”. May God be with him in order that he may know. Meanwhile, brethren, from a great fall he is being withheld, when he does not presume that he already knows, but has undertaken to know that which he knew not. For but now he was willing to appear as if knowing, and to declare that God has no care of things human. For this has come to be a most naughty and ungodly doctrine of unrighteous men. Know, brethren, that many men dispute and say that God cares not for things human, that by chances all things are ruled, or that our wills have been made subject to the stars, that each one is not dealt with according to his deserts, but by the necessity of his stars—an evil doctrine, an impious doctrine. Unto these thoughts was going that man whose feet were almost moved, and whose steps were all but overthrown, into this error he was going; but because he was not in tune with the generation of the sons of God, he undertook to know, and condemned the knowledge wherein with God's just men he agreed not. And what he says let us hear; how that he undertook to know, and was helped, and learned something, and declared it to us. “And I undertook,” he says, “to know.” “In this labour is before me.” Truly a great labour; to know in what manner both God does care for things human, and it is well with evil men, and good men labour. Great is the importance of the question; therefore, “and this labour is before me.” As it were there is standing in my face a sort of wall, but you have the voice of a Psalm, “In my God I shall pass over the wall.”
17....And he has done this; for he says how long labour is before him; “until I enter into the sanctuary of God, and understand upon the last things”. A great thing it is, brethren: now for a long time I labour, he says, and before my face I see a sort of insuperable labour, to know in what manner both God is just, and does care for things human, and is not unjust because men sinning and doing wicked actions have happiness on this earth; but the godly and men serving God are wasted ofttimes in trials and in labours; a great difficulty it is to know this, but only “until I enter into the Sanctuary of God.” For in the Sanctuary what is presented to you, in order that you may solve this question? “And I understand,” he says, “upon the last things:” not present things. I, he says, from the Sanctuary of God stretch out my eye unto the end, I pass over present things. All that which is called the human race, all that mass of mortality is to come to the balance, is to come to the scale, thereon will be weighed the works of men. All things now a cloud does enfold: but to God are known the merits of each severally. “And I understand,” he says, “upon the last things:” but not of myself; for before me there is labour. Whence “may I understand upon the last things”? Let me enter into the Sanctuary of God. In that place then he understood also the reason why these men now are happy.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)