Developing idea
A developing idea, defined in richards-2016 (par.45), is a term used to describe an idea that is not a basic idea but is also not a contrasting idea – it is in between. That is, it’s not the same, but it’s not totally different either.
As an amateur composer, the line is very blurry and what is said to be a “drastic change” does not immediately stand out as such to me.
Examples
ET: Main Theme
In this case, A2 changes its harmonic rhythm to 1 chord per measure which is supposedly a drastic change.

The Right Stuff: Main Theme
- End of
A2melody is nearly the same as the end ofAmelody - Harmony of both
A,A2is the same - Beginning melodic portion of
AandA2are different

Who’s Afraid of Virginia Woolf? Main Theme
- m2 of
A2is very different thanA - Harmony of
A+A2follows a standardI IIm V Iwhich connects them

Star Wars: Main Theme
- This uses the hinge technique that is common in many of John Williams’ works
- 2nd half of
Ais the 1st half ofA2
- 2nd half of

The Mission: Gabriel’s Oboe
- This one is much more loose
- The similarity lays within m2 and m3-m5
- m2 has a run that starts on D and ends up on A, all within m2
- m3 begins a run that pickups on A and goes up to D, then does a much more embellished movement down towards A, finally reaching A in m5
