"Count Apponyi recounts the evening of September 1, 1876, at Richard Wagner’s home, Wahnfried, during the first Bayreuth Festival.
“A few of us were together at Wahnfried after dinner. Wagner, being tired, had left the company, and Ferencz Liszt took the lead in a conversation which turned on Beethoven’s last sonatas. Liszt was very interesting on the subject. He spoke especially of the famous Hammerklavier, and more particularly of the fine adagio in F Sharp minor which it contains. In the midst of a sentence he stood up and exclaimed: - ‘I will prove it to you!’ - We retired to the music-room, which at Wahnfried reached from the ground level, past the first floor and up to the glass roof. On the first floor there is an open gallery, on which the bedroom doors open, and from which a spiral staircase leads down to the ground floor. In the middle of the hall stood the huge piano, at which Liszt sat down, and filled our souls with the mysticism of Beethoven’s last works…. Liszt seemed once more to have surpassed himself, to have established an inexplicable, direct contact with the dead genius whose interpretation for him was a religious task. When the last bars of the mysterious work had died away, we stood silent and motionless. Suddenly, from the gallery on the first floor, there came a tremendous uproar, and Richard Wagner in his nightshirt came thundering, rather than running, down the stairs. He flung his arms around Liszt’s neck and, sobbing with emotion, thanks him in broken phrases for the wonderful gift he had received.”"
— Lizst Plays Hammerklavier