mastery of orchestration. He attended the rehearsals with Glazunov, and followed the score. After hearing these performances, Rimsky-Korsakov devoted himself almost exclusively to composing operas for the rest of his creative life. Wagner's use of the orchestra influenced Rimsky-Korsakov's orchestration, beginning with the arrangement of the polonaise from Mussorgsky's Boris Godunov that he made for concert use in 1889. Toward music more adventurous than Wagner's, especially that of Richard Strauss and later Claude Debussy, Rimsky-Korsakov's mind remained closed. He would fume for days afterwards when he heard pianist Felix Blumenfeld play Debussy's Estampes and write in his diary about them, "Poor and skimpy to the nth degree; there is no technique, even less imagination." This was part of an increasing musical conservatism on his part (his "musical conscience", as he put it), under which he now scrutinized his music and that of others as well. Compositions by his former compatriots in The Five were not immune. While working on his first revision of Mussorgsky's Boris Godunov, in 1895 he would tell his amanuensis, Vasily Yastrebtsev, "It's incredible that I ever could have liked this music and yet it seems there was such a time." By 1901 he would write of growing "indignant at all [of Wagner's] blunders of the ear"—this about the same music which caught his attention in 1889. In 1892, Rimsky-Korsakov suffered a second creative drought, brought on by bouts of depression and alarming physical symptoms. Rushes of blood to the head, confusion, memory loss and unpleasant obsessions led to a medical diagnosis of neurasthenia. Crises in the Rimsky-Korsakov household may have been a factor—the serious illnesses of his wife and one of his sons from diphtheria in 1890, the deaths of his mother and youngest child, as well as the onset of the prolonged, ultimately fatal illness of his second youngest child. He resigned from the Russian Symphony Concerts and the Court Chapel and considered giving up composition permanently. After making third versions of the musical tableau Sadko and the opera The Maid of Pskov, he closed his musical account with the past; he had left none of his major works before May Night in their original form. Another death brought about a creative renewal. The passing of Tchaikovsky presented a twofold opportunity—to write for the Imperial Theaters and to compose an opera based on Nikolai Gogol's short story Christmas Eve, a work on which Tchaikovsky had