Transcendental Magic
Transcendental Magic by Eliphas Levi is said to be his Magnum Opus. Eliphas wrote over 60 books in his life-time, and every one was filled with wisdom.
In Transcendental Magic, he discusses real magic, (not to be confused with stage magic), and perfectly expounds upon this subject in an amazingly intelligent, articulate, and relatively concise manner.
This masterpiece is divided into two sections : The Doctrine of High Magic, and the Rituals.
This is a piece of literature to be studied, as it is extremely important, however I must insist that all except for VERY ADVANCED students of magic refrain from practicing ANYTHING written in the ritual section. It is extremely dangerous and should not be tampered with.
But It is important to read and understand both sections. For beginners, it will be like learning a new language. Do not move on without looking up that which you do not understand, or else the entire book will fall on deaf ears.
Enjoy!