Schumann studied with Dorn, the conductor at the civic theatre. Dorn recalled:

Having completed exercises in figured-bass realization, chorale harmonization, and canon, teacher and student moved on to double counterpoint. Intrigued by the mysteries of this discipline, and reluctant to tear himself away from his desk, Schumann once requested that his lesson take place in his own rooms. On arriving at Schumann’s flat, Dorn found his student poring over a sheaf of papers, at his side an uncorked bottle of champagne, which they then jointly consumed as a means of “moistening the dry work at hand.”

Letter to Wasielewski of 7 September 1856, in Eismann, Quellenwerk 1, p. 74.
Cited in: Daverio, John (1997) Schumann: Herald of a New Poetic Age. New York: Oxford University Press, p.70