Instruct: Classify Amazon reviews into positive or negative sentiment
Query: central to Jung's teaching

After studying the collected works for 20 years, and reading many Jungians, I've formed the opinion that this book is the linchpin of Jung's entire psychology. You won't get any closer to understanding his basic ideas than right here. The alchemical part of the book is quite arcane and not quite suited for Jung rookies, but the basics in this book make it essential.