How did Mozart reshape second themes during recapitulations?

In the context of sonata form, Wolfgang Amadeus Mozart is noted for his preference for strongly differentiated themes. When these themes reappear during the recapitulation, Mozart often reshapes his second subjects drastically.1

This practice serves the essential goal of sonata form: the reconciliation of opposites. While the exposition introduces a conflict by presenting the second subject in a dominant key, the recapitulation typically brings both subjects into the tonic key to establish a new state of equilibrium. By modifying the second theme, Mozart ensures it fits the tonic key perspective, often by making small adjustments to the transition material that originally led to the dominant. This approach highlights his mastery in managing the structural and tonal requirements of the form while maintaining thematic interest.21