Vic Fischer identified the quotation which Ira Noveck asked about on 16
August. I just wanted to add that "An Open Letter" was reprinted in the
Jumping Frog book (1867) as "A Complaint about Correspondents." It didn't
make the cut for Sketches, New and Old (1875) because Clemens deleted it
from the earlier (pirated) sketchbook, Choice Humorous Works (1873),
calling it "Rubbish."

Also, for a more discursive but very similar comment on children's
compositions, see "Letter from Mark Twain," 19 or 20 January 1864, Early
Tales & Sketches 1, pp. 333-38. I believe Lou Budd reprints this as "Miss
Clapp's School" in the first volume of his collected Tales and Sketches
(Library of America).

Bob Hirst