From the Christmas issue of the British Medical Journal:
[T]he condition that Wagner described as the “main plague of his life” was recurring headaches. The details presented in his writings and letters as well as the numerous diary records of his second wife, Cosima, confirm that Wagner had a severely disabling migraine disorder producing frequent migraine attacks, sometimes with aura...This from a letter written by Wagner to Liszt:
The first scene of act 1 of the opera Siegfried provides an extraordinarily concise and strikingly vivid headache episode. The music begins with a pulsatile thumping, first in the background, then gradually becoming more intense. This rises to become a directly tangible almost painful pulsation. While the listener experiences this frightening headache sensation, Mime is seen pounding with his hammer, creating the acoustic trigger for the musically induced throbbing, painful perception. At the climax Mime cries out: “Compulsive plague! Pain without end!”...
My health, too, is once more so bad, that for ten days, after I had finished the sketch for the first act of Siegfried, I was literally not able to write a single bar without being driven away from my work by most tremulous headaches.More at the link, including references to the scintillating auras in Wagner's music:
Mime, irritated, sings: “Loathsome light! Is the air aflame? What is it flaring and flashing, glittering and whirring, what is swirling and whirling there and flickering around? It glistens and gleams in the sunlight’s glow. What is it rustling and humming and blustering there?”Very interesting. You learn something every day.