[...] It is a great joy to me that you have recently seen Cornelius. I feel as if I had been present on the occasion myself. As far as I remember, you got to be very fond of Cornelius when you were on the Altenburg. It was not till we were in Vienna that I gradually began to get on terms with him, but I discovered at last that he is really a most rare and unusual person, both as regards character and intellectual abilities. Actually he is the only one of the younger men (though he is well on in the thirties) to whom I can attribute real genius. His temperance, modesty, contented mind and great moral worth, however, give him a place quite by himself. I could only wish that this lovable man would settle permanently with us, but he pursues his own independent plan of life, which I must respect.—Well, he will have told you a lot about me and my schemes. He and everyone else think it much the best thing for me to settle in Biebrich. The advantage of this lies in the fact that if I never mean to take a regular post in connection with a theatre again, it is most important that I should be able to visit them all readily, while actually residing in a quiet and retired spot. [...]
At Karlsruhe I talked with the Grand Duke for fully an hour. His wife had been taken ill. He will invite me to come again in a few days' time and, if possible—to conduct Lohengrin, too. I must say that at parting I grasped the amiable man's hand very heartily. It was obvious that he must have had his relation to me very much on his mind since the last letter (which I did not answer). He was really distressed and supposed I was angry with him. I found him strangely confused in his ideas as to my circumstances. [...]—Despite this really most charming, and (I doubt not) pregnant, resumption of relations with the Grand Duke, I have now entirely given up all idea of settling in Karlsruhe, chiefly on account of Devrient, whom I have not even visited this time. I could never get on very long with this stiff old pedant, who, on principle, never does anything but support the mediocre, and, furthermore, has done me constant injury by his infamous talk about the impracticability of Tristan. I should lose patience some time or other and—God! Peace and Quiet is my motto now! I might fly into a passion, you know, with such an old blockhead! It will be a different thing to go there now and then at the Grand Duke's invitation.—
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 517