Julian Siegel's new sax-playing friend, Mike Harris, showed him how this mysterious process worked
As well as the tune that was originally written to go with a song and its chords, there could be plenty of others.
Three chords, the Batman sequence. Right, what a great tune
Julian Siegel
The musician who has learned what notes sound OK with any particular chord (and maybe even some that don't sound OK, but can be added to make things more interesting along the way) can then play a completely new original melody over the same 'changes'.
When he left college, Julian Siegel's new bass-playing friend, Mike Harris, showed him how this mysterious process worked.