The last act is short and almost entirely taken up by Lohengrin's story and farewell. The scenery is the same as in the first act, and the entire chorus of noblemen and soldiers again assemble before the king. They have not yet heard of the tragic event which ended the last act, and are therefore surprised when a bier is carried in and placed solemnly before them. It bears the body of Frederick. They are still more surprised when Elsa enters, pale and dejected, and then their hero, who appears equally sad. But surprise reaches its climax when they hear him announce that he can not be their leader.
Lohengrin wastes no words. After the first assertion he informs them of Frederick's death; whereupon all voices declare his fate to be most just, and the body is removed. Lohengrin then announces that Elsa, his wife, has broken the vow which they all heard her make, and he has come before them to answer her question and dispel the mad suspicion which a wily tempter implanted in her heart. They shall all learn his name and heritage, and may then judge whether he was worthy of their trust. The people wonder with awe-hushed voices what revelation is in store, and then there floats in the orchestra the soft tremolo of the swan-music, as Lohengrin tells them of a distant land called Montsalvat, where is a radiant temple. And in this temple is guarded a sacred vessel which possesses wonder-powers. A dove descends from heaven once every year to renew its marvelous strength. This treasure-blessing is called the "Grail," and to its chosen votaries a matchless power is given. These knights of the Grail are sent abroad as champions of innocence and truth, and they may tarry so long as their name is unknown. But the Grail's blessing is too pure and holy to be regarded by common eyes, and if disclosed its champion must leave at once. Lohengrin adds that this penalty now falls on him, for he is a knight of the Grail: his father, great Parsifal, wears its crown, and "I am Lohengrin."
As in the first prelude and swan-song, the harmonies of this last great recital seem not of earth but from another sphere; they linger and abide with us like a beautiful blessing. This silver-clad knight of the Grail has been singing of a hallowed mystery whose purity and spirituality are revealed more in the music than by the words. After bidding farewell to the hapless Elsa, from whom he must part in spite of her piteous appeals, there comes gliding upon the river the swan-boat. He sings a sad welcome to the swan, and then announces to Elsa that could he have remained one year, through the mercy of the Grail her brother would have returned. He hands her his sword and horn and ring to give this brother if ever he comes back. The sword and horn will impart strength and victory, and the ring shall remind him of "Lohengrin who loved Elsa and was her champion."
A jarring interruption is now created by Ortrud, who cries out with reckless triumph that the swan who serves Lohengrin is the bewitched brother, and that Elsa has herself to thank for causing the hero's departure, which forever prevents the young Duke's return. On hearing this mocking invection from the sorceress, Lohengrin clasps his hands in a fervent prayer, which is at once answered. A dove descends from heaven and touches the swan, which is immediately changed into the young heir. He rushes forward to embrace his sister, while Lohengrin steps into the boat, which is drawn away by the dove. It floats silently down the beautiful river, and the hero stands sorrowfully leaning upon his silver shield. This is our last glimpse of Lohengrin, the Knight of the Grail.
"Aida"