8 “Your Righteousness is like the mountains of God: Your Judgments are a great deep”. Who are the mountains of God? Those who are called clouds, the same are also the mountains of God. The great Preachers are the mountains of God. And as when the sun rises, he first clothes the mountains with light, and thence the light descends to the lowest parts of the earth: so our Lord Jesus Christ, when He came, first irradiated the height of the Apostles, first enlightened the mountains, and so His Light descended to the valley of the world.
And therefore says He in a certain Psalm, “I lifted up my eyes unto the mountains, from whence comes my help.” But think not that the mountains themselves will give you help: for they receive what they may give, give not of their own. And if you remain in the mountains, your hope will not be strong: but in Him who enlightens the mountains, ought to be your hope and presumption. Your help indeed will come to you through the mountains, because the Scriptures are administered to you through the mountains, through the great Preachers of the Truth: but fix not your hope in them.
Hear what He says next following: “I lifted up my eyes unto the mountains, from whence comes my help.” What then? Do the mountains give you help? No; hear what follows, “My help comes from the Lord, which made Heaven and earth.” Through the mountains comes help, but not from the mountains. From whom then? “From the Lord, which made Heaven and earth.”...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)