4 But now in that which follows, “they have made Jerusalem for a keeping of apples;” even the Church herself is rightly understood under this name, even the free Jerusalem our mother, concerning whom has been written, “many more are the sons of the forsaken, than of her that has the husband.” The expression, “for a keeping of apples,” I think must be understood of the desertion which the wasting of persecution has effected: that is, like a keeping of apples; for the keeping of apples is abandoned, when the apples have passed away. And certes when through the persecuting Gentiles the Church seemed to be forsaken, unto the celestial table, like as it were many and exceeding sweet apples from the garden of the Lord, the spirits of the martyrs did pass away.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)