usician who
complained to him of the difficulty of a certain passage, and begged
him to alter it. "Is it possible to play those tones on your
instrument?" Mozart asked; and when he was told it was, he replied,
"Then it is your affair to bring them out."

Beethoven's way of mental composing appears at first sight to differ
widely from Mozart's. But if we had as many specimens of Mozart's
preliminary sketches as we have of Beethoven's, the difference would
perhaps appear less pronounced, and would to a large extent resolve
itself into the fact that Beethoven did not trust his memory so much
as Mozart did, and therefore put more of his _tentative_, or rough
sketches, on paper. He always carried in his pockets a few loose
sheets of music paper, or a number of sheets bound together in a
note-book. If his supply gave out accidentally, he would seize upon
any loose sheet of paper, or even a bill of fare, to note down his
thoughts. In a corner of his room lay a large pile of note-books, into
which he had copied in ink his first rough pencil-sketches. Many of
these sketch-books have been fortunately preserved, and they are among
the most remarkable relics we have of any man of genius. They prove
above all things that rapidity of work is not a test of musical
inspiration, and that Carlyle was not entirely wrong when he defined
genius as "an immense capacity for taking trouble." In the "Fidelio"
sketch-book, for example, sixteen pages are almost entirely filled
with sketches for a scene which takes up less than three pages of the
vocal score. Of the aria, "O Hoffnung," there are as many as eighteen
different versions, and of the final chorus, ten; and these are not
exceptional cases by any means. As Thayer remarks: "To follow a
recitative or aria through all its guises is an extremely fatiguing
task, and the almost countless studies for a duet or terzet are enough
to make one frantic." Thayer quotes Jahn's testimony that these
afterthoughts are invariably superior to the first conception, and
adds that "some of his first ideas for pieces which are now among the
jewels of the opera are so extremely trivial and commonplace, that one
would hardly dare to attribute them to Beethoven, were they not in
his own handwriting."

On the other hand these sketch-books bear witness to the extreme
fertility of Beethoven's genius. Thayer estimates that the number of
distinct ideas noted in them, which remained unused, is as large as
the number