Ambrose of Milan — as excerpted in the Catena Aurea on Luke 15:17-24

“Or by these words are signified the heavenly gifts of the Spirit impaired by the sin of the soul, or because from the bosom of his mother Jerusalem which is in heaven, he ought never to depart. But being cast down, he must by no means exalt himself. Hence he adds, I am no more worthy to be called thy son. And that he might be raised up by the merit of his humility, he adds, Make me as one of thy hired servants.”