Thomas Aquinas, on Ps 41:9

“In the daytime the Lord hath commanded his mercy; and a canticle to him in the night. With me is prayer to the God of my life.”

“Next the prayer is set forth: "And I will say to God: You are my protector," etc. In which he does two things. First he gives thanks for benefits received; second he inquires about the reason for the evils he suffers. First a man ought to acknowledge, because one who is not grateful for benefits received is unworthy of those yet to be received. Wis. 16: "The hope of the ungrateful," etc. And therefore he says, "You are my protector." Jerome has, "You are my rock," that is, my strength. And therefore he is called protector, for defending. Ps. 3: "But you, O Lord, are my protector," etc. Or, "You are my protector," that is, of my nature. Is. 42: "Behold my servant, I will uphold him." Or, "my protector in Baptism." Ps. 18: "He took me from many waters." And if you are my protector, I wonder at the evils I suffer. And first he inquires about the reason for the evils; second he sets forth certain things that are signs of the one and the cause of the other, at "While the enemy afflicts." From the evils he considers two things. One on the part of God: namely, that he seems to have forgotten him. Another on his own part, because he is oppressed by sadness. On the part of God, because he permits him to be afflicted; and therefore he says, "Why have you forgotten me?" because formerly you upheld me thus. Is. 49: "The Lord has forgotten me." But in truth he has not forgotten; on the part of him who was being afflicted, he says, "And why do I go about in sadness," that is, what is the reason that you give me over to sadness? Ps. 38: "All the day I went about in sadness, while the enemy afflicts me." Here he shows the pain he suffers from adversaries, and he assigns the effect of the persecution; as if to say: this is the cause why I go about in sadness, because I am afflicted by enemies—sometimes by temporal ones, sometimes by spiritual ones. Mt. 13: "An enemy has done this."”

Imported from an open dataset — not yet checked against the printed edition.