My Friend!
[...] Since the breakdown of my St. Petersburg negotiations I can no longer forbear to tell you that it was you who, without knowing it, helped me in the first terrible necessity to which my three Parisian concerts reduced me.
Just as it became necessary to pay at once the expenses of those concerts, which eventually amounted to over 11,000 francs, [...] the music-publisher [Schott], who had approached me about The Rhinegold, answered my letter, complying quite unexpectedly with the terms I offered them and sending me the required honorarium forthwith in a bill of exchange on Paris.
At the same time I heard from St. Petersburg that the director of the Imperial Theatre [von Saburov] would shortly come to Paris to try to get me to go to St. Petersburg next winter on advantageous terms.
You were far away and my situation was impossible; the concerts—once advertised—had to be carried through.
I spent the honorarium on The Rhinegold on the supposition that I should be able to repay you at once from the profits on the prospective St. Petersburg engagements; not till then should you be told of what had happened.
Now this prospect, too, has been closed to me. Accordingly I can no longer defer acquainting you with the circumstances.
I must dismiss as illusory every possibility of being able to reimburse you soon by other means. There is nothing left for me but to give you a receipt for the amount agreed between us for the last piece of The Nibelungs, whereby the 6000 francs for The Rhinegold may count as paid back to you. I shall finish this piece yet; for were this not my destiny I do not know what should keep me alive when I daily long for death with all my heart. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 468