Fans of Star Trek will recognize that acronym as “Infinite Diversity in Infinite Combination” – the heart of Vulcan philosophy.
It is in fact at the heart of our music here on Terra Firma as well. It is often said that there are only twelve notes (in the Western scale, at least). Yet out of those twelve notes, there are over 5.7 billion combinations.
Likewise with “changes,” or chord progressions. The Great American Songbook contains tens of thousands of pieces, ranging from the brilliant to the mediocre (the latter of which are still better than most of what passes for popular song in the 21st Century), and jazz, theater and cabaret performers work hard to learn as many of them as possible.
Yet the harmonic progressions of all of these great and not-so-great songs are made up of fewer than 35 different sequences.
Once the performer understands this, s/he realizes that learning the Great American Songbook is not as much of a challenge as it seems. One suspects that legendary performers such as the late Bobby Short (whose vast repertoire was nothing short of legendary) knew this on an instinctual level.
It can be learned, however.