9 “Let all Your works, O Lord, confess to You, and let Your saints bless You”. How so? Is not the earth His work? Are not the trees His work? Cattle, beasts, fish, fowl, are not they His works? Plainly they too are. And how shall these too confess to Him? I see indeed in the angels that His works confess to Him, for the angels are His works: and men are His works; and when men confess to Him, His works confess to Him; but have trees and stones the voice of confession?
Yes, verily; “let all” His “works confess to” Him. What do you say? Even the earth and the trees?...But there arises the same question in regard of praise, as in regard of confession. For if earth and all things devoid of sensation therefore cannot confess, because they have no voice to confess with; neither will they be able to praise, because they have no voice to proclaim with. But do not those Three Children enumerate all things, as they walked amid the harmless flames, who had leisure not only not to fear, but even to praise God?
They say to all things, heavenly and earthly, “Bless ye the Lord, praise Him and magnify Him for ever.” Behold how they praise. Let none think that the dumb stone or dumb animal has reason wherewith to comprehend God. They who have thought this, have erred far from the truth. God has ordered everything, and made everything: to some He has given sense and understanding and immortality, as to the angels; to some He has given sense and understanding with mortality, as to man; to some He has given bodily sense, yet gave them not understanding, or immortality, as to cattle: to some He has given neither sense, nor understanding, nor immortality, as to herbs, trees, stones: yet even these cannot be wanting in their kind, and by certain degrees He has ordered His creation, from earth up to heaven, from visible to invisible, from mortal to immortal.
This framework of creation, this most perfectly ordered beauty, ascending from lowest to highest, descending from highest to lowest, never broken, but tempered together of things unlike, all praises God. Wherefore then does all praise God? Because when you consider it, and see its beauty, thou in it praisest God. The beauty of the earth is a kind of voice of the dumb earth....And this which you have found in it, is the very voice of its confession, that you praise the Creator. When you have thought on the universal beauty of this world, does not its very beauty as it were with one voice answer you, “I made not myself, God made me”?
Source: The Enarrations, or Expositions, on the Psalms (New Advent)