From Benedict XVI’s reflection on Psalm 136:

[W]e can say: The liberation from Egypt, the time in the desert, the entrance into the Promised Land and then the other problems are very distant from us; they are not part of our history. But we must be attentive to the fundamental structure of this prayer [of this psalm]. The fundamental structure is that Israel remembers the Lord’s goodness. In its history, there are so many dark valleys, so many passages through difficulty and death, but Israel remembers that God is good, and they can overcome in the dark valley — in the valley of death — because they remember. Israel remembers the Lord’s goodness and His power; that His mercy endures forever.

And this is also important for us: remembering the Lord’s goodness. Remembering becomes the strength of hope. Remembering tells us: God is; God is good, and His mercy is eternal. And thus, remembering opens the road to the future — even in the darkness of a day, of a moment in time, it is the light and star that guides us. Let us, too, remember the good; let us remember God’s eternal, merciful love. Israel’s history is already part of our memory as well, of how God revealed Himself, of how He created for Himself a people to be His own. Then God became man, one of us: he lived with us, suffered with us, died for us. He remains with us in the Blessed Sacrament and in the Word. It is a history, a remembrance of God’s goodness that assures us of His goodness: His love is eternal.

You can read his entire meditation here.