"Astrological Key Words" by Manly P. Hall is a compilation of astrological terms and concepts drawn from various sources. It likely serves as a starting point for those interested in learning the basics of astrology.

Manly P. Hall (1901-1990) was a Canadian-born mystic, author, and lecturer. He is considered one of the 20th century's most influential figures in the field of esoteric philosophy. Hall's work focused on finding common threads across various spiritual and philosophical traditions.

Here are some of his key achievements:

* Founded the Philosophical Research Society in Los Angeles, a haven for exploring mystical wisdom.

* Authored over 150 books, with "The Secret Teachings of All Ages" being his most famous.

* Delivered thousands of lectures, making complex philosophical ideas accessible to a wide audience.