The counter to this interpretation is the truly remarkable fact that Schubert did not have regular access to a piano as he composed. Robert Winter, in the New Grove biographical sketch of Schubert, writes that in late 1824,"on his return to Vienna [from Zseliz] Schubert moved briefly – probably for financial reasons – for one last time into the Schubert family home in the Rossau. To be sure, it was the only place he ever lived in that contained a piano; Schubert never bought, leased or borrowed a piano of his own." Since he composed on a regular basis throughout the morning (one of the few disciplined parts of his life, apparently), this means that great swathes of Schubert's music were written "in his head," that is, without assistance from an instrument, at least not from a keyboard.[update 2-20-10: I am still trying to trace this history of Schubert's instrumentarium. Given that he was a proficient violinist, it's not unreasonable to assume that he would have owned that instrument, perhaps for most or all of his adult life, but so far I have found no reference in the literature. And, as to the piano, here is a bit of counter-evidence in a drawing by Moritz von Schwind, made in 1821 and called "Schuberts Zimmer."
end update]
This also means that playing for dancing might have been far less onerous than I suggested above, because Schubert might have happily used the time to make "sound experiments," to try out melodies -- or, more likely, progressions or key relations -- that he had already written or wanted to write but might not be able to auralize sufficiently. Maurice Brown's comment about the dances as "notebooks" for larger compositions, then, is on the mark but too text-oriented -- the dances as "sound experiments" would be a better description. [added text 12-19-09: Brown speculates that Schubert used casual dance improvisations "as 'journals' or 'notebooks' in which the composer was able to try out...new ideas and techniques that might later be developed in more substantial pieces" (Brown cited in Brodbeck 32). Brian Newbould follows out this idea by making comparisons between dances and some of Schubert's sonata movements.]
References:
Brodbeck, David. "Dance Music as High Art: Schubert's Twelve Ländler, op. 171 (D. 790)." In Walter Frisch, ed., Schubert: Critical and Analytical Studies, pp. 31-47. Lincoln: University of Nebraska Press, 1986.
[added] Dieckmann, Friedrich. Franz Schubert: eine Annäherung. Frankfurt am Main: Insel Verlag, 1996.
Newbould, Brian. "Cornered in the Middle Eight: Dance Miniaturism vis-à-vis Sonata." In Newbould, ed. Schubert the Progressive: History, Performance Practice, Analysis, 107-116. Aldershot: Ashgate, 1998.
