13 “You have visited the earth, and hast inebriated it”. Whence hast inebriated the earth? “Your cup inebriating how glorious it is!” “You have visited the earth, and hast inebriated it.” You have sent Your clouds, they have rained down the preaching of the truth, inebriated is the earth. “You have multiplied to enrich it.” Whence? “The river of God is filled with water.” What is the river of God? The people of God. The first people was filled with water, wherewith the rest of the earth might be watered. Hear Him promising water: “If any man thirst, let him come to Me and drink: he that believes in Me, rivers of living water from his belly shall flow:” if rivers, one river also; for in respect of unity many are one. Many Churches and one Church, many faithful and one Bride of Christ: so many rivers and one river. Many Israelites believed, and were fulfilled with the Holy Spirit; from thence they were scattered abroad through the nations, they began to preach the truth, and from the river of God that was filled with water, was the whole earth watered. “You have prepared food for them: because thus is Your preparing.” Not because they have deserved of You, whom You have forgiven sins: the merits of them were evil, but You for Your mercy's sake, “because thus is Your preparing,” thus “You have prepared food for them.”
14. “The furrows thereof inebriate You”. Let there be made therefore at first furrows to be inebriated: let the hardness of our breast be opened with the share of the word of God, “The furrows thereof inebriate You: multiply the generations thereof.” We see, they believe, and by them believing other men believe, and because of those others believe; and it is not sufficient for one man, that having become himself a believer, he should gain one. So is multiplied seed too: a few grains are scattered, and fields spring up. “In the drops thereof it shall rejoice, when it shall rise up.” That is, before it be perchance enlarged to the bulk of a river, “when it shall rise up, in its drops,” that is, in those meet for it, “it shall rejoice.” For upon those that are yet babes, and upon the weak, are dropped some portions of the sacraments, because they cannot receive the fullness of the truth. Hear in what manner he drops upon babes, while they are rising up, that is, in their recent rising having small capacities: the Apostle says, “To you I could not speak as if to spiritual, but as if to carnal, as if to babes in Christ.” When he says, “to babes in Christ,” he speaks of them as already risen up, but not yet meet to receive that plenteous wisdom, whereof he says, “Wisdom we speak among perfect men.” Let it rejoice in its drops, while it is rising up and is growing, when strengthened it shall receive wisdom also: in the same manner as an infant is fed with milk, and becomes fit for meat, and nevertheless at first out of that very meat for which it was not fit, for it milk is made.
15. “You shall bless the crown of the year of Your goodness”. Seed is now sowing, that which is sown is growing, there will be the harvest too. And now over the seed the enemy has sown tares; and there have risen up evil ones among the good, false Christians, having like leaf, but not like fruit. For those are properly called tares, which spring up in the manner of wheat, for instance darnel, for instance wild oats, and all such as have the first leaf the same. Therefore of the sowing of the tares thus says the Lord: “There has come an enemy, and has sown over them tares;” but what has he done to the grain? The wheat is not choked by the tares, nay, through endurance of the tares the fruit of the wheat is increased. For the Lord Himself said to certain workmen desiring to root up the tares, “Suffer ye both to grow unto the harvest.”...Conquer the devil, and you will have a crown. “You shall bless the crown of the year of Your goodness.” Again he makes reference to the goodness of God, lest any one boast of his own merits. “Your plains shall be filled with abundance.”
16. “The ends of the desert shall grow fat, and the hills shall be encircled with exultation”. Plains, hills, ends of the desert, the same are also men. Plains, because of the equality: because of equality, I say, from thence just peoples have been called plains. Hills, because of lifting up: because God does lift up in Himself those that humble themselves. Ends of the desert are all nations. Wherefore ends of the desert? Deserted they were, to them no Prophet had been sent: they were in like case as is a desert where no man passes by. No word of God was sent to the nations: to the people Israel alone the Prophets preached. We came to the Lord; the wheat believed among that same people of the Jews. For He said at that time to the disciples, “You say, far off is the harvest: look back, and see how white are the lands to harvest.” There has been therefore a first harvest, there will be a second in the last age. The first harvest was of Jews, because there were sent to them Prophets proclaiming a coming Saviour. Therefore the Lord said to His disciples, “See how white are the lands to harvest:” the lands, to wit, of Judæa. “Other men,” He says, “have laboured, and into their labours you have entered.” The Prophets laboured to sow, and you with the sickle have entered into their labours. There has been finished therefore the first harvest, and thence, with that very wheat which then was purged, has been sown the round world; so that there arises an other harvest, which at the end is to be reaped. In the second harvest have been sown tares, now here there is labour. Just as in that first harvest the Prophets laboured until the Lord came: so in that second harvest the Apostles laboured, and all preachers of the truth labour, even until at the end the Lord send unto the harvest His Angels. Aforetime, I say, a desert there was, “but the ends of the desert shall grow fat.” Behold where the Prophets had given no sound, the Lord of the Prophets has been received, “The ends of the desert shall grow fat, and with exultation the hills shall be encircled.”
17. “Clothed have been the rams of the sheep”: “with exultation” must be understood. For with what exultation the hills are encircled, with the same are clothed the rams of the sheep. Rams are the very same as hills. For hills they are because of more eminent grace; rams, because they are leaders of the flocks....“They shall shout:” thence they shall abound with wheat, because they shall shout. What shall they shout? “For a hymn they shall say.” For one thing it is to shout against God, another thing to say a hymn; one thing to shout iniquities, another thing to shout the praises of God. If you shout in blasphemy, thorns you have brought forth: if you shout in a hymn, you abound in wheat.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)