[...] Accept my most cordial thanks for your letter which I have just received! Sad as is the circumstance of which it treats, yet I breathe again to know that my poor wife is in your hands, under your care. May Heaven bless you if you can continue to give me such comfort as you have this time been able to indicate. You would not believe how much good you do me by this care for the sufferer!—But what I chiefly want to tell you is simply that you may count absolutely on my moral co-operation in this course of treatment. By separation for a time I have achieved the object I instinctively sought—that is, I am now in a position to exercise a calming and conciliating influence upon her mind. Even when we were actually living together this was my firm intention latterly in view of her melancholy state of health, and yet the agitation, the excitement of the moment, would now and then get the better of me, the more so that I, too, have an irritable nature and that these everlasting useless, senseless vexations imposed much very real suffering on me.
Here, at a distance, I can choose the hour and the mood when I am entirely master of myself and can handle my purpose with full loyalty to my duty. This encourages me to hope for the best.—For the rest, believe me, there is not, and never has been any question of serious matrimonial differences. Rather, my torment was that she put a wrong construction on much that went on in my mind and heart simply because—to speak frankly—she is incapable of understanding the real truth of these things. This great intellectual difference is indeed the source of many painful misunderstandings between us. Happily I can now get the peace of mind necessary to deal with her and I hope that my last letter will have contributed greatly to soothe her spirit. I shall go on, steadfastly. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 376