Dear Kapellmeisterin!
[...] I have kept on working on The Valkyrie a little it is true, but it is going much more slowly than I thought it would at first. What I finally put down is always the best I can do; only the right moods for the work come more and more rarely in this dreary life of mine. As long as I wrote books and made verse, it did well enough, but for music I need another kind of life; I need Music herself; but I am like one who wants to kindle a fire and has the flame but not the necessary wood. Added to this, the subject of The Valkyrie affects me far too painfully; really there is not a sorrow in the world that does not find its most agonising expression herein. But I have to pay for the artistic handling of these sorrows. I became quite ill again over it several times and had to give up altogether. I am now in Act II. at the scene where Brynhilde goes to Siegmund to tell him he must die—one can scarcely call this kind of thing "composition"!—If only I can get on to Young Siegfried; that will be a quicker matter, no doubt.—[...]
Source: Letters of Richard Wagner, Vol. 1, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 270