[...] On the whole I am feeling somewhat dull-witted and morose. I have been engaged on this work too long, and I feel very much as though my creative powers are still feeding on the shoots and blossoms which were produced over a short period as though by some fructifying storm. As a result I cannot really get down to any truly creative work; the longer it takes, the more favourable my mood must remain if my inner resources are to be kept alert, and these moods cannot be provoked at will on the strength of mere reflection, as so much else can, especially in relation to the world. It is true that I work every day, but only briefly and there is little to show for it, just as the flashes of inspiration are brief and few in number; often I would prefer to do nothing at all, were it not that I am spurred on by my dread of a totally empty day.
[...]
Source: Selected Letters of Richard Wagner, trans. and ed. Stewart Spencer and Barry Millington (W. W. Norton & Company, 1988), No. 240