[...] I have been not inappropriately admonished in several quarters to make public my arrangement of Gluck's Iphigenia in Aulis. I have duly completed this arrangement for the Dresden Court Theatre; having first altered the text in the most important passages, and having then cut out the French affectations, I brought the principal scenes into close association with each other, and did away with old-fashioned trimmings; on the other hand I put what is essential and really beautiful in the most favourable light, uniting the broken separate pieces by a dramatically conceived ritornelle, and lastly I substituted for the old trivial finish a quite new close in the spirit of the Euripidean "Iphigenia." I revised the instrumentation and the accompaniment with the greatest care, and I freshly composed bridge passages, certain closes and even, in Act III., an important incident in the action of the Iphigenia. In making this adaptation my object was to give back to the modern stage this opera of Gluck, now almost forgotten on the boards (for when an Iphigenia by Gluck is given, it is nearly always the Iphigenia in Tauris), not simply as a curio to interest the expert in classical music [...], but as a real popular success, to be felt and admitted by everyone. This object I attained completely. [...] What I now offer you for publication is a full pianoforte arrangement of the opera, to be completed by Herr Uhlig or Herr von Bülow to my satisfaction; this being comparatively small in bulk would not put you to great expense. You would have to let me prepare a copy of the score (the original of which is in the possession of the Dresden Court Theatre) to be sent in case of demand to the theatres (without further payment to me). Perhaps, however, it would be a good thing to have lithographed copies made. [...] I have noticed how quickly we come to an end with so-called classical operas when proposals have to be made to well-disposed theatres, and an extension in this direction would certainly be very desirable.—I would require twenty-five louis d'or as honorarium for myself, for which sum the score would become your absolute property. [...]
I have still to write to you about my Faust Overture. I think—and my friends are of the same opinion—that it is one of my best purely musical compositions. Formerly, being pre-occupied with opera, I attached little importance to the work and had almost forgotten it. Liszt has brought it to the light of day with great effect, and if I am to make myself known to the concert-going German public I could not, in my opinion, recommend myself better than by means of this composition which I would again thoroughly revise for purposes of publication. I could only decide upon this revision, however, if I knew that it had been accepted by a good publisher willing to pay a good price, and accordingly I now ask whether you would care to publish and what sum you could pay me. I would see to getting a very good pianoforte arrangement through Bülow. [...]
Source: Letters of Richard Wagner, Vol. 1, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 230