Of the mystic books I've read, this one is one of my favourites.
In it, the pathways of the Jewish Kabbalist Tree of Life and the Hebrew letters and Tarot cards assigned to these pathways become a rich playground full of symbolic mysticism and archetypical analogies played across multiple cultures. In addition to this, guided meditations exist for each pathway represented in this book, giving you the chance to enjoy the rich pathways and archetypes of your own consciousness.
For best results, I recommend using this book with the Celestial Tarot by Kay Stevonton and Brian Clark. The archetypes and letters represented in this book are actually on those cards, and as a result this particular deck is incredible for pathwork.