I suddenly feel like beating around the bush a little here. So please bear with me.
Picture this: You graduated from high school, went to college, left your high school's sweetheart behind, found a new girl, then another one, then yet another... (I could go on and on), graduated from college, got a job, and (with any luck) married one of the girls you dated in college. Twenty years had gone by, you suddenly found yourself at the high school reunion party. A glance at your old-time highschool sweetheart all of sudden brought back a world of love and hope. Whew! What gives?! You suddenly found how attractive and desirable your highschool sweetheart was! (And if fate played tricks on you, beside her was a 300-pound hairy-chested, bald-headed husband of hers...)
So what does all that have anything to do with this book, you ask?
Well, it has EVERYTHING to do with this book. As you WILL agree with me, to become an artist in any "respectable" medium (oil, watercolor, pastel, and the likes), one has to start with drawing. The most highly-disciplined practice is figure drawing. Usually, one would start with drawing the likeness, USING LINES. Then comes positive, negative spaces, mass, tone, then colors, etc.
In this book, however, the author presents an approach of drawing figures using charcoal as medium and using mass (rather than LINES) to achieve the effects.
The book is well-written and very readable. I finished the book from cover to cover at one sitting of several hours.