Israel Regardie wrote The Tree of Life, a book many consider his magnum opus, in 1932. It has continued to sell for decades. And no wonder. Up until the time this book was published, very little information about true high magic was available to the public.
In this book, Regardie reveals the secrets of real magic. He begins with an explanation of what magic is and, just as importantly, what magic is not. He explains that it is a spiritual study and practice which, along with forms of yoga, forms the two branches of the tree that is mysticism. Magic is not being a medium or a psychic. Then he explains the tools of the magician, what they mean, and how to use them. He explains the techniques of evocation and invocation, skrying, and astral travel. He shows how the Qabalah unites everything. He even gives a description of the secrets of sexual magick. All of this is in a clear, lucid writing style. This book is simply a must for anyone who is, or aspires to be, a real magician.