Hi Ram,

What do you mean by categorize?
do you mean, for instance, we are setting up a music library and we want to establish the most efficient card catalogue?
or something more like: how are all these beloved pieces of music arranged into constellations in the mind?
or something else?

I'll try to answer one of these, which may or may not be the one you had in mind. :-)

I was once in a library where all the books were arranged alphabetically by the author's last name. Extremely efficient for shelving and disastrous for browsing (well, except for completely random browsing). For an artist with a particular musical skill who is looking for something to play, categorizing in the way you did (which is really also about instruments, as well as competencies in various styles) would be extremely useful.

On the other hand for me personally, as a listener music is so closely bound up with emotions and moods that my categories would be very different, much less rational perhaps. Jazz in a run-down nightclub in Paris (the kind they used to have in the 20th) is to me more like rembetiko than the bright brassy jazz of a summer afternoon in the park, for instance. I'll stop short of suggesting that we organize by color-coding...though that's probably not far from how I actually think. 

This reminds me of something Benjamin says, that the revenge which cities take on people is that a person's memory of any encounter or conversation is never purely of the encounter itself, but always also of the scene around it.

Originally, I was referring to how the world of music is disected by genres as viewed by someone that would like to play a piece of music. But actually your interpretation of my original question, poses a more broad/interesting question.

So now we have two:

1)   Genre (classical, Jazz, Pop, Rock, other)

2)   Mood (sad, delightful, exciting, invigorating, etc)

Both categorizations (anybody has additional ones?) could be fragmented I guess to hundreds of sub- categories. I’m looking I guess for the ~5 big ones in each categorization (like the 5 big animals in the Africa safari that one must see to make the trip complete)

I am still distracted by the fact that I think the question of how to categorize is philosophically fascinating, and music is a particularly good example of this. But if you're less interested in the abstract question, let me know.

Some thoughts on the issue of categorizing, then. There is an obvious system in place, the academic study of music. One can for instance look at the way the study of music is organized into courses:

http://www.juilliard.edu/asp/occ/course_search.php?div=M

at introductory syllabi:
http://omnidisc.com/MUSIC/Syllabus.html

at the way that orchestras are broken down into sections, at tables of contents of music books...

I'm not sure the "five animals to see on the safari" question is the same one at all. If there happen to be six astonishingly beautiful elephants all alive at the time at which you happen to take your safari perhaps you should just see the elephants. :-)