If You Could Buy Only One Composition Book, Which One Would It Be?

I would prefer to buy the books I would read, and have them phisically, so now that I've started searching for doing my compositional knowledge more wide I want to buy one book next month. Then I would read it and think of buy a new one etc.

The question is which book would you buy to start with the right foot? I've been recommended to buy Theory of harmony of Arnold Schoenberg or Fundamentals of Musical Composition, by the same author. Are this good choices to start with?

Life of Beethoven by Romain Roland 

Actually it is not about composition theory but it is about how an artist should be, it can help you with all of your later troubles in life

But talking technically Schoenberg's "Composition" book is good as far as I have read it , some books take music creating as a silly and easy task but Schoenberg sees it as a devoted artist should see music , it's not something that you can rely on "For Dummies" or etc...this is a serious job.

and if you are a pirate you can use this link :

http://thepiratebay.sx/torrent/4630039/Books_on_Music_Theory_(Harmony__Counterpoint__Orchestration)_[in

This link contains a lot of good books in music and composition but you should be a pirate to use it! (it is illegal in some countries but not mine)

Schoenberg's Fundamentals is a good choice. Theory of Harmony too, but I would use another harmony book before this because in my opinion the language is very very formal, it's an extra difficulty.

Later on, look over counterpoint and orchestration books too. 

Toss up:

The Complete Arranger / Sammy Nestico

Inside The Score / Rayburn Wright

I agree. Theory of Harmony is very hard. Though it can be done in small incremiments. I would start with Strcutures of tonal music first or Pratical Guide to Harmony by Trychiaschsy,  Matter of fact, as much as you can...gain different pov.  :)

The Well-Tempered Clavier.