Okay, so I'm getting the hang of this. Anyway, the first "Theme" of Mozart's 21st Piano Concerto is plain to me. But where does the second begin? And what is it? Again, I have to write a paper on this, and besides a VERY basic, rudimentary comprehension, I have no technical understanding of music. :(

I cant point to the bar. I don't have the music, but it is described here.

http://en.wikipedia.org/wiki/Piano_Concerto_No._21_(Mozart)

No worries! I'll do my best to help you understand the second theme of Mozart's 21st Piano Concerto.

In classical music, a concerto usually consists of several sections, and each section has its own distinct musical ideas called "themes." The first theme is typically the main musical idea, while the second theme contrasts with it.

To identify where the second theme begins, you can listen for a change in mood or musical material. In Mozart's 21st Piano Concerto, the second theme typically begins following a section called the "transition." The transition acts as a bridge between the first theme and the second theme. It often involves a change in key, tempo, or texture, setting the stage for the second theme to enter.

The second theme of a concerto usually brings a contrasting musical idea. It might have a different melody, rhythm, or harmonic progression compared to the first theme. In Mozart's 21st Piano Concerto, the second theme is often more lyrical and melodic, presenting a new musical idea that complements or contrasts with the first theme.

To analyze the specific timing of the second theme in Mozart's 21st Piano Concerto, I suggest referring to the score or a recording with a clear delineation of the sections. You can follow along with the different sections, focusing on the transition, and listen for the distinct musical material that marks the entrance of the second theme.

Remember, listening to the piece multiple times and paying attention to the structure and changes in the music will help you identify and understand the second theme more effectively. Good luck with your paper!