The book is a marvel. I read the first edition when I was in college and it taught me more than two semesters of basic drawing taught by an indifferent "modern" artist. In most books that try to teach drawing as a mechanical process, as opposed as a purely "creative" exercise, they seem to leave out a "magic" step that makes things possible. Turns out that it isn't magic, but it is fairly subtle. The books makes a process explicit that is too often left to subliminal happenstance.

Don't mistake, the process is still hard, and requires much effort, but it does remove a lot of the magic feather aspect.