Since 1891 the plan of the work had been
entirely remodelled, as proved by the rough drafts still extant. The
author had given up the idea of describing different instruments from
their technical standpoint, and was more anxious to dwell upon the
value of tone qualities and their various combinations.

Among the author's papers several forms of the book have been found,
each widely differing in detail from the other. At last, in the summer
of 1905 Rimsky-Korsakov brought his plans to a head, and outlined the
six chapters which form the foundation of the present volume. But the
work suffered a further interruption, and the sketches were once more
laid aside. In his _Memoirs_, Rimsky-Korsakov explains the fact by
lack of interest in the work and a general feeling of weariness: "The
treatise remained in abeyance. To start with, the form of the book was
not a success, and I awaited the production of _Kitesh_, in order to
give some examples from that work" (p. 360).

Then came the autumn of 1906. The composer experienced another rush of
creative energy; his opera, _The Golden Cockerel_ made rapid strides,
and kept him busy all that winter and the following summer. When it
was finished, in the autumn of 1907, his thoughts reverted to the
treatise on orchestration. But the work made little progress. The
author had his doubts as to the adequacy of the plan he had adopted,
and, in spite of the entreaties of his pupils and friends, he could
not bring himself to broach the latter part of the book. Towards the
end of 1907 Rimsky-Korsakov was constantly ailing in health, and this
materially affected his energy. He spent the greater part of his time
reading old notes and classifying examples. About the 20th of May
he set out for his summer residence in Lioubensk, and having just
recovered from a third severe attack of inflammation of the lungs,
began to work on the first chapter of the treatise in its present,
final form. This chapter was finished on June 7/20, about 4 o'clock in
the afternoon; the same night, the composer was seized with a fourth
attack which proved fatal.

The honour fell on me to prepare this last work of Rimsky-Korsakov for
publication. Now that _Principles of Orchestration_ has appeared in
print I think it necessary to devote a few words to the essential
features of the book, and to the labour imposed upon me in my capacity
as editor.

On the first point I will say but little. The reader will observe from
t