Well, I too have been so low in health again recently that, since I finished the rough draft for the first act of Siegfried ten days ago, I have literally been unable to write down another note without being chased away from work by the most agonising headaches. So every morning I sit down, stare at the paper, and am lucky in the end if I can manage Walter Scott. It is simply that I have over-exerted myself again, but how am I to recover my strength? I got on well with The Rhinegold, but I had great trouble even with The Valkyrie and now I am like a pianoforte badly out of tune, as regards my nervous system - and I have got to hammer out Siegfried upon it. A pretty state of things! This last, I imagine, will break the strings ultimately and then all will be over. Well, we cannot alter matters but really it is a dog's life!
Richard Wagner
Source: Letters of Richard Wagner, Volume 1, ed. Altmann/Hull (London: Dent, 1927), No. 327