I must tell you at once about a really funny discovery that I have just made. It has suddenly occurred to me that all my anguish over my work is the result of hypochondria. Everything which I have sketched out seems to me so horribly bad that I lose all eagerness and want to go no farther. To-day I forced myself to make a fair copy of a passage from my rough draft, which recently displeased me so much that I thought I should have to rewrite it entirely. However, no improvement occurred to me and I was so unhappy about it that I thought of giving up altogether, etc. Well, at last, in despair, I make a fair copy of the passage to-day, leaving it exactly as in the sketch, except for a few unimportant details of correction. I play it over to myself and—discover that it is so good that I could make nothing better!—Isn't that laughable? And yet it is a bad state of things, for this hypochondria, which is growing upon me, is a proof that all is not as it should be. I just cannot bring myself to put feeling and warmth into working up my rough sketches. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 411