This book deals with a very important and specific aspect of composition and improvisation. However, its brevity is painful in parts. It's objectives are confused: the first twenty pages provide a hand-holding softly-softly approach to the basics of music theory, which I'd assume you'd have already studied before seeking out and diving into scale-chord relationships in any sort of detail. The remaining twenty pages deal with the actual subject matter of the text in a dense and in places poorly written manner. The number of errors in terms of spelling, grammar, one of the chord charts and even in the answer section is, frankly, disgraceful. Having already studied music and the guitar for some years now it is immensely frustrating to see what should be a brilliantly useful text, a penetrating study of the said title, actually be little more than an introduction to a few areas where there are golden nuggets of useful knowledge and conceptual musical analysis to be found. Moreover there are in many sections far too few example with which to study. I want to give this book 5 stars simply because somewhere beneath the poor execution is very worthwhile subject matter, but as I am reviewing the book and not the subject matter itself I'm afraid it must get merely 3. If you already have a good knowledge of music theory and want to rehearse and perhaps discover a few new possibilites then do buy this book. It is a can of worms to be opened with caution by those who know what they are doing and perhaps best not by the enquiring novice.