This book is unfortunately a little out of date with many of the current practices, and omits important information regarding gematria as it is applied by the order. However, it is an amazing introduction to many of the most important concepts regarding the foundational practices and the methodology of practioners. As an interesting side note, it used to be common for ANY person who owned a copy of this book to AUTOMATICALLY be awarded the 9th degree (aka 'Thrice Blessed'). THAT is how IMPORTANT the order regarded this book.