Singing indicates that the person is passing beyond the boundaries of the merely rational and falling into a kind of ecstasy; the merely rational he can express in ordinary language (that is why overly rational people are seldom tempted to sing). Now singing finds its climactic form in the Alleluia, the song in which the very essence of all song achieves its purest emodiment.... In fact we are dealing here with something that cannot be translated. The Alleluia is simply the nonverbal expression in song of a joy that requires no words because it transcends all words. In this it resembles certain kinds of exultation and jubilation that are to be found among all peoples, just as the miracle of joy manifests itself in every nation.... What does it mean to sing with "jubilation"? It means: to be unable to express in words, or to verbalize, the song that sings to you in your heart. As the harvesters in field or vineyard experience an increasingly jubilant sense of joy, they become incapable, it seems, of finding words to express this overflowing joy. They abandon syllables and words, and their singing turns into a jubilus or cry of exultation. A jubilus is a shout that shows the heart is trying to express what it cannot possibly say. And to whom is such a jubilus more fittingly directed than to him who is himself ineffable? He is ineffable because your words cannot lay hold of him.... The Alleluia is like a first revelation of what can and shall someday take place in us: our entire being shall turn into a single immense joy.

Pope Benedict XVI