Maj7 chord notation, triangle from Coltrane?

I've read that too, is it from Mark Levine's "The Jazz Theory Book"?

 

A) Does anyone know if this book is still in circulation (even used)?
(What's it called?)
B) Could someone explain the triangle? It's a mystery to me.

Thanks!

Edit - Nevermind, I just bought the only used copy I could find.

 

O that triangle! Duh! I knew that. I've always hated that ---almost as much as using upper or lower case "M"s to denote major or minor. What's so hard about spelling out Maj7, Min7, Dim7, Aug7? All the Ms and ms and +s and circles get kinda' annoying.

 

It all boils down to who's doing the charting. Where it first came from, I don't know.

Have you ever seen how Allan Holdsworth writes his chord symbols??? Whew!

 

I have the Holdsworth Vid where he introduces that system. More proof of my suspicion that that guy's from Mars!

 

I prefer the symbols.

 

The triangle in "C triangle" is borrowed from the five limit lattice of tones used in the study of just intonation. The triangles left hand base indicates the tonic; the right hand corner of the triangle is the Pythagorean tripling of the frequency of the tonic, or fifth; the top of the triangle is the quintupling of the frequency of the tonic, or the just major third.

The literal interpretation of this symbol would then be "a just major triad built on the fifth degree of the tonic." Or in conventional terms, the slash chord G over C. C major 7, 9. In popular use, the terminology obviously survives today as C major 7.

John Coltrane was kind enough to leave us this clue into his thought process... it's worth investigating. Please don't let the 12 edo interval space alphabetized lists of descriptions "music theory" crap eat your breadcrumbs. This is Harmony.