Dignus est Agnus, qui occisus est, accipere virtutem, et divinitatem, et sapientiam, et fortitudinem, et honorem. Ipsi gloria et imperium in saecula saeculorum.
“Worthy is the Lamb that was slain, to receive power and divinity and wisdom and strength and honor. Glory and dominion be to him until the ages of ages.” (Rev 5:12)
Click here to listen to an audio of the chant, sung by Liborius Lumma, Innsbruck (Austria).
The solemnity of Christ the King was introduced in 1925, so there are no original Gregorian pieces. Dignus est Agnus was compiled from the (much longer) introit Dum sanctificatus (which we did not have in this series, since it is only one of two options on the third Sunday in Lent). After the Second Vatican Council, Dignus est Agnus remained in the repertory for the Eucharist as one of very few neo-compositions.
With my personal prejudice about such neo-compositions I cannot find anything special or ingenious about this introit. But what I really like is the text itself that the Church chose for this solemnity: Christ’s reign is not a reign of brutal revenge, destruction, or bossiness. Christ’s reign is the reign of a slain and victimized lamb. No king in the world, no ruler in the Church should ever forget that—and should have a look at the Gospel reading of this very day: Matt 25:31–46.