Thank you for these recommendations.
There are so many books that have made an impact on me, but I will give you the names of two that immediately came to mind.
The first is A Beginner's Guide to Constructing the Universe by Michael S Schneider - a book that blew my mind and made me realize how powerful numbers are - far more powerful than the run-of-the-mill numerologists would understand.
The second is A Garden of Pomegranates by Israel Regardie. This book was my first step in exploring tarot and understanding that tarot is not meant for divination, but has a much deeper purpose.