O friend!
You really cause me nothing but anxiety at present, and this is just because I think so much of you! Strictly speaking, you are the one and only gain life has brought me so far, aside from my beloved wife. Fortunately, Fidi has now been added to my blessings, but there is a gap between us which only you can fill—something like the relationship of a son to a grandchild. I have no anxiety about Fidi, but I am greatly concerned about you, and in so far, about Fidi also. This concern is of a rather commonplace character. I wish for nothing so much as your physical wellbeing, since everything else seems to be now assured. Day after day, I have carefully re-read the Birth, and at each reading I say to myself: "If he only regains his health and keeps it, and if everything goes well with him in other ways—for things must not go wrong with him." How gladly would one do something to help matters along!
This has set me to thinking anew as to how a beginning could best be made, and it is this uncertainty which causes my anxiety. But hold out a little longer, and sooner or later the right way is bound to be found. I should have unbounded confidence, and my fears would be turned into hopes, could I only hear that you had the proper amount of confidence in yourself, that you are encouraged about your health, and that you are in good spirits.
I have not been able to find anything in my "letters" to indicate that I have blazed a path for you (as you say), but, on the contrary, it seems to me as if I had done nothing but hang an additional burden about your neck. Nor did I mean to say that it was necessary for you to "ripen" for your task, but only that your own work will keep you fully occupied as long as you live.
Nothing but Tristan will still interest you. But take off your glasses! You must pay attention to nothing but the orchestra. Adieu, dear, well-beloved friend! Shall we not see each other soon?
Source: The Nietzsche-Wagner Correspondence, ed. Elizabeth Foerster-Nietzsche, trans. Caroline V. Kerr (Boni and Liveright, 1921), No. 29