11 In this Psalm we have chiefly exhorted you to do deeds of alms, because it is thence that we ascend; and you see that he who ascends, sings the song of steps. Remember: do not love to descend, instead of to ascend, but reflect upon your ascent: because he who descended from Jerusalem to Jericho fell among thieves....The Samaritan as He passed by slighted us not: He healed us, He raised us upon His beast, upon His flesh; He led us to the inn, that is, the Church; He entrusted us to the host, that is, to the Apostle; He gave two pence, whereby we might be healed, the love of God, and the love of our neighbour. The Apostle spent more; for, though it was allowed unto all the Apostles to receive, as Christ's soldiers, pay from Christ's subjects, that Apostle, nevertheless, toiled with his own hands, and excused the subjects the maintenance owing to him. All this has already happened: if we have descended, and have been wounded; let us ascend, let us sing, and make progress, in order that we may arrive.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)