[...] To-day I am asking both yourself and Niemann a question, and the possibility of repeating the performances in Bayreuth depends first and foremost on your answers. Will you spare me another six weeks or so next summer? I for my part am prepared to undertake these performances only if I am able to promise you a very considerable sum for expenses, the amount to be settled by yourself.
To my very lasting and painful regret, you were the only one who went away without taking leave of me! For the second time you deprived me of the long-desired moment in which I had promised myself the pure satisfaction of telling you, frankly and openly, of recognition and gratitude such as I have owed to few others in the course of my life. The first time was at the banquet after the first performance, when I proposed to take as the subject of my speech the peculiar character of German art and of its disciples, their energy, their industry, their consuming devotion to their task, through which the most brilliant achievements of other nations may be surpassed, and to take the liberty of adducing you and your performance as Wotan as an example of all this. On that occasion my artistes left me in the lurch, and I had to talk only of matters concerning our patrons. I hoped for a parting word with you. How unkindly you cheated me of it!
Believe me, this to me unaccountable behaviour is the real sting in the sense of worry which I bear about with me to this day! God knows what was in your mind. Let it remain unexplained, unless I can clear up some misunderstanding or other on your part. But one good action would dispel all the clouds. Meet me in this—and I shall see everything in a better and pleasanter light again!
Try to wriggle out of it as you may, you shall hear me tell you one thing here and now, namely that our Mastersingers was the best thing I have ever produced on the stage. Your Hans Sachs was to me incomparable and unforgettable—your Mark was perfect—your Wotan amazing. I have to use the term over and over again. No performance I have ever seen compares with yours in the second act of The Valkyrie—even taking into account the unprecedented difficulties caused by its sheer length and range. Let this be established between us, even if you should set out to forget me. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 694