12 All this, from the beginning of the Psalm up to this verse, we have heard of the oil of the press. What remains is rather for grief and warning: for it belongs to the lees of the press, even to the end; perchance also not without a meaning in the interposition of the “Diapsalma.” But even this too is profitable to hear, that he who sees himself already of the oil may rejoice; he that is in danger of running among the lees may beware. To both give heed, choose the one, fear the other.
“Hear, O My people, and I will speak, and will bear witness unto you”. For it is not to a strange people, not to a people that belongs not to the press: “Judge ye,” He says, “between Me and My vineyard.”
13. “Israel, if you shall have heard Me, there shall not be in you any new god”. A “new god” is one made for the time: but our God is not new, but from eternity to eternity. And our Christ is new, perchance, as Man, but eternal God. For what before the beginning? And truly, “In the beginning was the Word, and the Word was with God, and the Word was God.” And our Christ Himself is the Word made flesh, that He might dwell in us. Far be it, then, that there should be in any one a new god. A new god is either a stone or a phantom. He is not, says one, a stone; I have a silver and a gold one. Justly did he choose to name the very costly things, who said, “The idols of the nations are silver and gold.” Great are they, because they are of gold and silver; costly they are, shining they are; but yet, “Eyes they have, and see not!” New are these gods. What newer than a god out of a workshop? Yea, though those now old ones spiders' webs have covered over, they that are not eternal are new. So much for the Pagans....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)