[...] You ask after The Twilight of the Gods? After many tiresome interruptions, I completed the composition of this work last summer. Since then I have been so exhausted by constant anxieties and exertions in respect of my big undertaking that I must still put off my working out of the score. [...]
I may now tell you [...], as my publishers, that from June 1st onwards you will get regular consignments of the score of The Twilight of the Gods. May I ask you to be so good as to put the printing in hand at once and proceed vigorously? You can then send the separate scenes as they are ready (perhaps in proof) to Klindworth in Moscow. If we work thus together uninterruptedly (as most definitely I personally propose to do), we may count on having all ready by Easter 1874. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 661