[...] Will you please relinquish any musical manuscripts of mine you may possess in view of my wife's enthusiasm? At the time of my desperate departure from Vienna, I gave you (and also Tausig and Cornelius—if I am not mistaken?) manuscripts which I thought burdensome and unnecessary. To you (?) I gave the rough draft of the composition of Love Forbidden. Be magnanimous and do not interpret the despairing act of that moment as a premeditated transaction conferring possibly profitable rights on you. Although those were terrible days, my memory of them also embraces recollections of the truest and most devoted friendship, for you, my dear Heinrich, are among them. Now that sorrow has given place to utterly unlooked-for bliss, I feel so immeasurably indebted to the bringer of this bliss that I can boldly ask the friends who suffered with me then to do homage to her, even at real cost to themselves. [...]
[...] You must work more with me, and that as a musician, for we have philosophers enough. I will soon tell you what you have to do. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 713