Thomas Aquinas — on 2Cor 1:9 (Commentary on 2 Corinthians)

“He amplifies the reason for his affliction when he says, but that was to make us rely not on ourselves, i.e., that human pride should be repressed: "O Lord, my strength and my stronghold" (Jer. 16:19), and that we trust God in all things: "Blessed is the man who trusts in the Lord, whose trust is the Lord" (Jer. 17:7). And therefore he says, but on God who raises the dead: "The Lord kills and brings to life" (1 Sam. 2:6).”