H.P. Blavatsky 
The Key to Theosophy [EPUB ebook] 

The Key to Theosophy is a foundational text of the Theosophical movement, written by
Helena Petrovna Blavatsky in 1889. It is presented in a question-and-answer format between a Seeker and a Theosophist, making it an accessible introduction for newcomers to Theosophy.
Helena Petrovna Blavatsky (1831–1891), often referred to simply as H.P. Blavatsky or HPB, was a Russian-born spiritual teacher, author, and the co-founder of the Theosophical Society. She is widely regarded as one of the most influential figures in the revival of esoteric and occult traditions in the modern Western world.