Historians might pursue E. T. A. Hoffmann's instructive review of 1813 (in Charlton 1989: 300-324), and learn that he considers what I call motives X and Y to be the first and second themes of the movement, although he is apparently unaware of their inversional relationship. Hoffmann's review of the opus 70 piano trios, along with his more famous review of the Fifth Symphony, may be credited with demonstrating the organic, motivic generational process through which Beethoven develops his larger heroic-period forms. Hoffmann concentrates on the "ingenious, contrapuntal texture" of the development, which he presents in full score (not otherwise available for study in this form at the time of his article). He also mentions crucial modulations and even provides a figured bass reduction of the rewritten transition in the recapitulation -- a forerunner of a Schenkerian linear Zug analysis. Hoffmann is also willing to comment on the character of my theme Y, noting that it "expresses a genial serenity, a cheerful, confident awareness of its own strength and substance." I think we might be in general agreement with his assessment, although he offers us no particular reasoning to support it.
Well, what more needs to be said? We have historical warrant for both our theoretical analysis and expressive interpretation of the passage, and we have mined its secrets with respect to the implied German augmented sixth in m. 6, the noncongruence of thematic and tonal arrivals in mm. 7 and 11, respectively, and even the clever derivation of Y from X. What more could semiotics offer, assuming we've done our homework thus far?
A great deal more. Because what I have presented thus far is only analogous to parsing a poem, analyzing its syntax, and offering a subjective impression of one of its moods. Unless we blithely accept Schenker's insistence that pitch structure, with a little metric interpretation thrown in, reveals the "true content" of music (as Schenker implies in the title to one of his Meisterwerk essays, "Beethovens 3. Sinfonie zum erstenmal in ihren wahren Inhalt dargestellt" [my italics]), I think we need to keep asking ourselves how the structures we have discovered might be based on typical meanings in the style, and how they might be creating unique kinds of meanings within the constraints of that style. In my work on Beethoven (Hatten, 1994), I call the first kind of meaning a stylistic correlation, and it is based upon the generalization of types; the second kind of meaning I term a stylistic interpretation, and it is based upon the creation of tokens. One way to explore these meanings is to investigate structural oppositions, which take on an asymmetrical character of marked vs. unmarked, and which allow us to map an opposition in musical structure more rigorously to an opposition in musical meaning. An example will be helpful.