For those who would like to explore the essence of The Secret Doctrine, or who have had difficulty penetrating its two large volumes, An Invitation to The Secret Doctrine should prove welcome. Based on Blavatsky's study suggestions given to her personal students, it is a succinct and appealing statement of the SD's principal teachings in her own words. Included are the Bowen notes of HPB's comments, relevant pages from The Secret Doctrine, photographs of HPB's manuscript, a historical account of 'The Writing of The Secret Doctrine' by Kirby Van Mater, and a glossary of terms.
Helena Petrovna Blavatsky (Russian: Еле́на Петро́вна Блава́тская, Yelena Petrovna Blavatskaya, often known as Madame Blavatsky; 12 August [O.S. 31 July] 1831 – 8 May 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.
A good introduction to Blavatsky's principal work, with exerpts, an historical essay, and suggestions from Blavatsky on an approach for studying The Secret Doctrine.