Name of the classical music from first time in Fishstick's library?

This is the part of the film where the Princess and Fishstick first realize they are in love - the scene opens with a sweep of the library scored with a piece of classical music which I've heard before (the clarinet solo is particularly memorable), but I've never been able to identify.

I know Fishstick later tells Hellboy he's listening to Vivaldi, but the part I'm thinking of comes before that scene.

Any help would be appreciated, and thanks.

Found it: Mozart clarinet concerto in A major K. 622 (2nd movement)