4 “He has founded the earth upon its firmness”. He has founded the Church upon the firmness of the Church. What is the firmness of the Church, but the foundation of the Church. What is the foundation of the Church, but that of which the Apostle says, “Other foundation can no man lay but that is laid, which is Christ Jesus.” And therefore, grounded on such a foundation, what has she deserved to hear? “It shall not be bowed forever and ever.” “He founded the earth on its firmness.” That is, He has founded the Church upon Christ the foundation. The Church will totter if the foundation totter; but when shall Christ totter, before whose coming unto us, and taking flesh on Him, “all things were made by Him, and without Him was not anything made;” who holds all things by His Majesty, and us by His goodness? Since Christ fails not, “she shall not be bowed for ever and ever.” Where are they who say that the Church has perished from the world, when she cannot even be bowed....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)