11 Have not men then somewhat reserved with God, which beasts deserve not, and whereunto beasts arrive not? They have evidently. And where is that which they have. “The children of men put their trust under the shadow of Your wings.” Attend, my Beloved, to this most pleasant sentence; “You save man and beast.” First, he spoke of “man and beast,” then of “the children of men;” as though “men” were one, “the children of men” other. Sometimes in Scripture children of men is said generally of all men, sometimes in some proper manner, with some proper signification, so that not all men are understood; chiefly when there is a distinction. For not without reason is it here put; “O Lord, You save man and beast: but the children of men;” as though setting aside the first, he keeps separate the children of men. Separate from whom? Not only from beasts, but also from men, who seek from God the saving of beasts, and desire this as a great thing. Who then are the children of men? Those who put their trust under the shadow of His wings. For those men together with beasts rejoice in possession, but the children of men rejoice in hope: those follow after present goods with beasts, these hope for future goods with Angels....
12. “They shall be satiated with the fullness of Your House”. He promises us some great thing. He would speak it, and He speaks it not. Can He not, or do not we receive it? I dare, my Brethren, to say, even of holy tongues and hearts, by which Truth is declared to us, that it can neither be spoken, which they declared, nor even thought of. For it is a great thing, and ineffable; and even they saw through a glass darkly, as says the Apostle, “For now we see through a glass darkly; but then face to face.” Lo, they who saw through a glass darkly, thus burst forth. What then shall we be, when we shall see face to face? That with which they travailed in heart, and could not with their tongue bring forth, that men might receive it. For what necessity was there that he should say, “They shall be satiated with the fullness of Your House”? He sought a word whereby to express from human things what he would say; and because he saw that men drowning themselves in drunkenness receive indeed wine without measure, but lose their senses, he saw what to say; for when shall have been received that ineffable joy, then shall be lost in a manner the human soul, it shall become Divine, and be satiated with the fullness of God's House. Wherefore also in another Psalm it is said, “Your cup inebriating, how excellent is it!” With this cup were the Martyrs satiated when going to their passion, they knew not their own. What so inebriated as not to know a wife weeping, not children, not parents? They knew them not, they thought not that they were before their eyes. Wonder not: they were inebriated. Wherewith were they so? Lo, they had received a cup wherewith they were satiated. Wherefore he also gives thanks to God, saying, “What shall I render unto the Lord for all His benefits towards me? I will take the cup of Salvation, and call upon the Name of the Lord.” Therefore, Brethren of men, let us be children and let us trust under the shadow of His wings and be satiated with the fullness of His House. As I could, I have spoken; and as far as I can I see; and how far I see, I cannot speak. “And of the torrent of Your Pleasure shall Thou give them to drink.” A torrent we call water coming with a flood. There will be a flood of God's Mercy to overflow and inebriate those who now put their trust under the shadow of His wings. What is that Pleasure? As it were a torrent inebriating the thirsty. Let him then who thirsts now, lay up hope: whoso thirsts now, let him have hope; when inebriated, he shall have possession: before he have possession, let him thirst in hope. “Blessed are they which do hunger and thirst after righteousness, for they shall be filled.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)