Helena Blavatsky 
There is no Religion Higher than the Truth 
The Secret Doctrine, The Key to Theosophy, The Voice of the Silence, Studies in Occultism, Isis Unveiled

This edition reveals the archaic truths which are the basis of all religions. It also uncovers the fundamental unity from which everything springs and shows the Occult side of Nature that has never been approached by the Science of modern civilization.
Isis Unveiled
The Secret Doctrine
The Key to Theosophy
The Voice of the Silence
Studies in Occultism
From the Caves and Jungles of Hindostan
Nightmare Tales

About the author

Helena Petrovna Blavatsky (1831 – 1891) was a Russian occultist, philosopher, and author who co-founded the Theosophical Society in 1875. She gained an international following as the leading theoretician of Theosophy, the esoteric religion that the society promoted. Informally, she is also widely known as Madame Blavatsky.