20 “The wind shall go over on it, it shall not be; and the place thereof shall know it no more”. For he is not speaking of grass, but of that for whose sake even the Word became grass. For you are man, and on your account the Word became man. “All flesh is grass:” “and the Word was made flesh.” How great then is the hope of the grass, since the Word has been made flesh? That which abides for evermore, has not disdained to assume grass, that the grass might not despair of itself.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)