2 “Save me, O Lord, for the holy has failed;” that is, is not found: as we speak when we say, Corn fails, or, Money fails. “For the truths have been minished from among the sons of men”. The truth is one, whereby holy souls are enlightened: but forasmuch as there are many souls, there may be said in them to be many truths: as in mirrors there are seen many reflections from one face.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)