10 Then he mentions, that they may praise the Lord, “mountains and hills, fruitful trees and all cedars”: “beasts and all cattle, creeping things, and winged fowls”. Then he goes to men; “kings of the earth and all people, princes and all judges of the earth”: “young men and maidens, old men and young, let them praise the Name of the Lord”. Ended is the praise from heaven, ended is the praise from earth. “For His Name only is exalted”. Let no man seek to exalt his own name. Will you be exalted? Subject yourself to Him who cannot be humbled. “His confession is in earth and heaven”. What is “His confession”? Is it the confession wherewith He confesses? No, but that whereby all things confess Him, all things cry aloud: the beauty of all things is in a manner their voice, whereby they praise God. The heaven cries out to God, “You made me, not I myself.” Earth cries out, “You created me, not I myself.” How do they cry out? When you regard them, and findest this out, they cry out by your voice, they cry out by your regard. Regard the heavens, it is beautiful: observe the earth, it is beautiful: both together are very beautiful. He made them, He rules them, by His nod they are swayed, He orders their seasons, He renews their movements, by Himself He renews them. All these things then praise Him, whether in stillness or in motion, whether from earth below or from heaven above, whether in their old state or in their renewal. When you see all these things, and rejoicest, and art lifted up to the Maker, and gazest on “His invisible things understood by the things which are made,” “His confession is in earth and heaven:” that is, thou confesses to Him from things on earth, thou confesses to Him from things in heaven. And since He made all things, and nought is better than He, whatsoever He made is less than He, and whatsoever in these things pleases you, is less than He. Let not then what He has made so please you, as to withdraw you from Him who made: if you love what He made, love much more Him who made. If the things which He has made are beautiful, how much more beautiful is He who made them. “And He shall exalt the horn of His people.” Behold what Haggai and Zachariah prophesied. Now the “horn of His people” is humble in afflictions, in tribulations, in temptations, in beating of the breast; when will He “exalt the horn of His people”? When the Lord has come, and our Sun is risen, not the sun which is seen with the eye, and “rises upon the good and the evil,” but That whereof is said, To you that hear God, “the Sun of Righteousness shall rise, and healing in His wings;” and of whom the proud and wicked shall hereafter say, “The light of righteousness has not shined unto us, and the sun of righteousness rose not upon us.” This shall be our summer. Now during the winter weather the fruits appear not on the stock; you observe, so to say, dead trees during the winter. He who cannot see truly, thinks the vine dead; perhaps there is one near it which is really dead; both are alike during winter; the one is alive, the other is dead, but both the life and death are hidden: summer advances; then the life of the one shines brightly, the death of the other is manifested: the splendour of leaves, the abundance of fruit, comes forth, the vine is clothed in outward appearance from what it has in its stock. Therefore, brethren, now we are the same as other men: just as they are born, eat, drink, are clothed, pass their life, so also do the saints. Sometimes the very truth deceives men, and they say, “Lo, he has begun to be a Christian: has he lost his headache?” or, “because he is a Christian, what gains he from me?” O dead vine, you observe near you a vine that is bare indeed in winter, yet not dead. Summer will come, the Lord will come, our Splendour, that was hidden in the stock, and then “He shall exalt the horn of His people,” after the captivity wherein we live in this mortal life....
11. “An hymn to all His Saints.” Know ye what an hymn is? It is a song with praise of God. If you praise God and singest not, you utter no hymn: if you sing and praisest not God, you utter no hymn: if you praise anything else, which pertains not to the praise of God, although you sing and praisest, you utter no hymn. An hymn then contains these three things, song, and praise, and that of God. Praise then of God in song is called an hymn. What then means, “An hymn to all His Saints”? Let His Saints receive an hymn: let His Saints utter an hymn: for this is what they are to receive in the end, an everlasting hymn....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)