Cassiodorus

“A canticle of David, when the house was built after the captivity.” So far as the literal sense is concerned, the heading points to the time when the temple at Jerusalem is known to have been refurbished by Zerubbabel, son of Salathiel, after it had been leveled to the ground by a hostile band of Chaldeans. But since he says nothing of this kind in what follows, and since the headings of psalms are never at variance with their content, it remains for us to investigate it in the spiritual sense. A destroyed house is built up when a soul following the captivity of sin begins to return to an understanding of the truth through the generosity of the Lord. This house, which is the universal church in which Christ dwells, is always raised up on living stones, because every day it gains increase in building from its confessors and does not cease to be built up until the number of the predestined is attained at the end of the world. We must store this psalm in our minds as the second of those proclaiming the first and the second coming of the Lord.