Instruct: Classify Amazon reviews into positive or negative sentiment
Query: One of the most important books ever written!

Although I disagree with a few of the exercises in this work (especially allowing beings to use your hand to write mediumistically), overall this text of self-development is one of the most important ever. It ranks with the exercises in Rudolf Steiner's work (although Steiner's meditations on plants are much safer overall) as the clearest path of development for those who are so inclined. Even if a person only progressed to stage 3 during a single lifetime, one has already taken an important first step. If you like this kind of thing, you might also enjoy the esoteric novel, "The Shattering Light of Stars" by Hicks.