These final four psalms have one thing in common: praise. Here is what C. S. Lewis has to say about praise in the psalms….
It has all the cheerful spontaneity of a natural, even a physical, desire. It is gay and jocund. They are glad and rejoice (9, 2). Their fingers itch for the harp (43, 4), for the lute and the harp—wake up, lute and harp!—(57, 9); let’s have a song, bring the tambourine, bring the “merry harp with the lute”, we’re going to sing merrily and make a cheerful noise (81, 1, 2). Noise, you may well say. Mere music is not enough. Let everyone, even the benighted gentiles, clap their hands (47, 1). Let us have clashing cymbals, not only well tuned, but loud, and dances too (150, 5). Let even the remote islands (all islands were remote for the Jews were no sailors) share the exultation (97, 1).
I am not saying that this gusto—if you like, this rowdiness—can or should be revived. Some of it cannot be revived because it is not dead but with us still. It would be idle to pretend that we Anglicans are a striking example. The Romans, the Orthodox, and the Salvation Army all, I think, have retained more of it than we. We have a terrible concern about good taste. Yet even we can still exult. The second reason goes deeper. All Christians know something the Jews did not know about what it “cost to redeem their souls”. Our life as Christians begins by being baptized into a death; our most joyous festivals begin with, and centre upon, the broken body and the shed blood. There is thus a tragic depth in our worship which Judaism lacked. Our joy has to be the sort of joy which can coexist with that; there is for us a spiritual counterpoint where they had simple melody. But this does not in the least cancel the delighted debt which I, for one, feel that I owe to the most jocund Psalms. There, despite the presence of elements we should now find it hard to regard as religious at all, and the absence of elements which some might think essential to religion, I find an experience fully God-centred, asking of God no gift more urgently than His presence, the gift of Himself, joyous to the highest degree, and unmistakably real. What I see (so to speak) in the faces of these old poets tells me more about the God they and we adore. (Reflections on the Psalms, 51-53)