from Piero Weiss (ed.), Letters of Composers Through Six Centuries (Philadelphia: Chilton Books, 1967), 125-26.

         I believe I already wrote you in my last letter that the Duc de Guines, whose Daughter is my Pupil in Composition, plays the flute surpassingly well, and she the Harp magnificently; she has a great deal of Talent, and genius, and in particular an incomparable memory, for she plays all her pieces by heart - 200 of them, in fact.  But she seriously doubts whether she also has any genius for Composition - especially with regard to thoughts - ideas; but her father (who, between ourselves, dotes on her a little too much) says she most certainly has ideas; that it’s just bashfulness - that she just lacks self-confidence.  Well, we shall see.  If she gets no ideas or thoughts (for at the moment she hasn’t any at all), then there is no help for it - goodness knows I cannot give her any.  It is not her father’s intention to make a great Composer of her; she need not (he said) write any operas, any arias, any Concertos, any Symphonies, but merely grand Sonatas for her instrument and mine.  I gave her her 4th Lesson today, and I’m tolerably pleased with her where the Rules of Composition and part-writing are concerned - she set me a pretty good Bass part under the first Minuet I wrote down for her.  Now she’s already begun to write in 3 parts.  It is going quite well, but she is soon Bored; only I cannot help it, I cannot possibly move on: it’s too early, even if the genius were really there, but unfortunately it is not - it will all have to be done artificially.
         She has no ideas at all.  Nothing will come.  I have Tried all kinds of things with her; among others, it occurred to me to write down quite a simple Minuet and see whether she might not be able to make a variation on it.  Well, that was of no use.  Now then, thought I, she just doesn’t know how to go about - and so I began a variation, just on the first bar, and told her to go on in the same vein and to stick to the idea; this, at last, went pretty well.  When she had finished, I asked her to be so good as to begin something herself - just the top part, a Melody.  Well, she brooded for a quarter of an hour - and nothing came.  So then I wrote down 4 bars of a Minuet and said, “Just see what an Ass I am!  Here I’ve begun a Minuet and can’t even finish the first part of it!  Do be so Kind as to complete it for me.”  This she believed to be impossible.  Finally, after much effort, something was brought forth; I was glad indeed that for once something had come.