I have seen a reference to a letter from Tchaikovsky to von Meck that in
part discusses his perceived deficiencies in compositional form, as well
as efforts to correct those weaknesses. I cannot find the letter, and
wondered if someone could post the relevant passages (if the letter
I know the passage you mean, and can find several translations of it,
but none of them cite the actual source. This version appears in
Tchaikovsky: A Symposium (1945), p. 26:
"All my life I have been much troubled by my inability to grasp and
manipulate form in music. I fought hard against this defect and can
say with pride that I achieved some progress, but I shall end my days
without having written anything that is perfect in form. What I write
has always a mountain of padding: an experienced eye can detect the
thread in my seams and I can do nothing about it"
The author of this article (Martin Cooper) quotes the above in the
context of other letters to Nadezhda von Meck, but without giving any
more details. I have a feeling that it is also quoted somewhere in David
Brown's 4-volume Tchaikovsky: A Biographical and Critical Study
(1978–91), but I haven't yet managed to track it down...
Many thanks. I believe that was the translation and context I had
seen, but I'm happy to have the actual text.