Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Pure intellectual stimulation.

Immortality, the nature of conciousness, the nature of reality, and more. This book is hard science fiction at its very best. I cannot think of another book to rival this one in terms of pure intellectual stimulation. Egan takes a few simple ideas and runs with them as well as anyone writing today. The writing is wonderful, the characters are interesting, but oh! the ideas, the ideas are grand! This book took me forever to read; so many times I would read a paragraph then stare into space and think about the ramifications and possibillities. This book should appeal to anyone with an interest in physics, artificial intelligence, and philosophy, or anyone who enjoys thinking about about what it means to be, especially what it means to be YOU