[...] I still owe you one more declaration of obligation on my part in regard to the money advances I have already received and still hope to receive from you, and I will put it in writing in this letter without further delay.
Accordingly, I recognise and declare myself pledged from henceforth to sell none of my musical works, finished or to be finished, [...] to any music-publisher, or to publish them printed or engraved in any other way whatsoever, without informing you or having given you the first refusal [...]
Following upon this, my new big comic opera, The Mastersingers of Nuremberg, upon which I am engaged at present, will be next at your disposal. [...]
[...] My poem is making strides, and by the end of this month, January, I think of recrossing the Rhine with the whole libretto ready for composition. The hopes I have of my work have steadily increased. The first two acts having shaped as they have done, I am now sure of quite extraordinary success. I hope this will not seem chimerical to you when I—as I hope to do in a fortnight's time—read you the whole work, which when finished takes on an aspect very different from that of the faint indications of a first rough sketch. The music is already complete in my brain. God grant I may soon get between four walls, where I can once more evoke the tones of my dear friend the Erard, which is still standing here in the packing-case! [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 515