[...] Accept my sincerest thanks for your recently notified acceptance of all my conditions for the sale to you of The Rhinegold. [...]
Each subsequent drama in my Nibelung cycle shall, in the first place, be offered to you, and I pledge myself in advance to ask no more for any one of them than for The Rhinegold. If, nevertheless, you should demonstrably have made a poor bargain with this first work you will find me ready even to abate my demands. I have only one thing further to ask you. Oblige me extremely by remitting me the whole amount, 10,000 francs, at once—by return, indeed.
On this point I have something to tell you. I confess that—after your last letter—I foresaw that you would ultimately agree to my terms. The possibility of having the sum of money in question almost immediately at disposal, induced me to engage in an enterprise which I regard as of great importance for my future success in Paris, and on that account I decided to venture a considerable sum as soon as it was in my power to do so. It concerns, in the first place, three big concerts which I am preparing to give at the Salle Ventadour with a very sumptuous display of artistic talent. The expenses and commitments involved are tremendous, and I have already undertaken them all in the hope—of not being left in the lurch by you. [...]
Accordingly, if I may consider all business matters as settled between us [...] I will close by telling you of a project I have—as yet a secret from everyone—of arranging, if all goes well, a first performance of The Rhinegold in May next year at the Salle Ventadour, with a cast chosen from among the foremost German dramatic singers. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 454