9 May then the Lord open to us that knock; and may the secret things of His mysteries, as far as Himself vouchsafes, be disclosed. For in order that the earth might be moved to the Truth when into the desert of the Gentiles the Gospel was passing, “the Heavens dropped from the face of God.” These are the Heavens, whereof in another Psalm is sung, “The Heavens are telling forth the glory of God.”... So here also, “the Heavens dropped;” but “from the face of God.” For even these very persons have been “saved through faith, and this not of themselves, but God's gift it is, not of works, lest perchance any man should be lifted up. For of Himself we are the workmanship,” “that makes men of one mood to dwell in a house.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)