Dearest Franz,
Klindworth has just played your great sonata to me. We passed the day alone together; he dined with me, and after dinner I made him play. You were with me; the sonata is beautiful beyond anything, grand and sweet, deep and noble, sublime as you are yourself. It moved me most deeply, and the London misery was forgotten all at once. More I cannot say, not just after having heard it, but of what I say I am as full as man can be. Once more, you were with me! Ah, could you soon be with me wholly and bodily, then we might support life beautifully. Klindworth astonished me by his playing; no lesser man could have ventured to play your work to me for the first time. He is worthy of you. Surely, surely, it was beautiful.
Richard Wagner
Source: Project Gutenberg eBook #4234, Correspondence of Wagner and Liszt — Volume 2, No. 184