[...] You must not be so very offended with me over the Kaisermarsch business. Some time ago Peters's "Bureau de musique," of which I knew nothing whatever, made me a spontaneous offer of 1500 francs for such a March if I would write one. Indeed, it was this which first put the idea into my head. I should probably never have thought of it otherwise. The unexpected fee was uncommonly opportune, as I had in view a journey to Germany with my wife, and absolutely no money on which to make it, as my circumstances are still, on the whole, somewhat straitened. To you [...] I am still actually in debt for advances, and I could not very well expect you to pay me cash on this occasion. I accepted the offer, then, because it chimed in almost too pat with my wishes, and though I thought of you and thought that you would not like it, I believed, too, that—you would end by forgiving me!—Well, now, I ask your pardon! [...]
[...] I now propose to work (chiefly in Berlin) to get a performance of The Ring of the Nibelungs exactly according to my own ideas, which would make a kind of national undertaking of it. On April 28th I am going to lecture there at the Royal Academy "On the Destiny of Opera," and I shall, besides, get influential friends to begin to move on my behalf. You, my most esteemed friend, will have an important part to play in this enterprise, and I want to discuss it with you personally. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 646