Thomas Aquinas, on Ps 42:2

“For thou art God my strength: why hast thou cast me off? and why do I go sorrowful whilst the enemy afflicteth me?”

“"Because you are my God." Here the reason for the deliverance is set forth; and it is twofold: one on God's part, who has the power; hence he says, "you are my strength." Is. 12: "My strength and my praise is the Lord." And He is called our strength effectively, because it comes from Him. Is. 40: "He gives power to the faint, and to those who have no strength He multiplies fortitude and vigor." The other reason is on his own part, namely the evils he suffers. Some evils we suffer according to opinion, because when we are in adversities we seem to be rejected by God; hence he says, "why have you rejected me?" But "the Lord will not cast off His people," Ps. 94. And so this evil is merely apparent. Another evil is real; hence there follows, "why do I go about in sadness?" Sad either with the sorrow of the world, which works death; and in this sense the meaning is: why do I go about in sadness, namely temporally, while the enemy, the evil man, afflicts me temporally. Or "I go about in sadness," with the good sorrow that works repentance unto salvation. And in this sense the meaning is: why do I go about in sadness only? Because joy should also be joined to repentance.”

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