The Theosophical Society was founded in New York in 1875 by Helena Petrovna Blavatsky (HPB), Henry Steel Olcott and William Quan Judge. Its stated objects were to form a universal brotherhood of humanity without distinction of race, creed or sex; to study comparative religion, philosophy and science; and to investigate the unexplained laws of nature and the powers latent in the human being. In practice, it became the most significant conduit for Eastern spiritual philosophy into the Western world in the 19th and early 20th centuries.
Blavatsky's two great works — Isis Unveiled (1877) and The Secret Doctrine (1888) — synthesised Hindu, Buddhist, Kabbalistic, Neoplatonic and Hermetic sources into a comprehensive cosmological system. The Secret Doctrine in particular presented what Blavatsky claimed was the "Secret Wisdom" underlying all the world's religious traditions — a perennial philosophy transmitted through a lineage of adepts she called the Mahatmas or Masters of the Ancient Wisdom.
The seven-body system was developed and refined by Blavatsky's successors — particularly Charles Webster Leadbeater and Annie Besant, who claimed clairvoyant perception of the subtle bodies and produced detailed accounts of their structure and function. Leadbeater's The Inner Life, The Astral Plane and The Mental Plane, and Besant and Leadbeater's Thought-Forms, remain among the most detailed accounts of subtle body anatomy ever written — whatever one makes of the clairvoyant methodology on which they are based.
The Theosophical system draws heavily on Hindu concepts (the koshas, the planes of existence) and Buddhist concepts (the various subtle bodies, the between-life state) while synthesising them into a specifically Western framework. It is a synthesis rather than a direct transmission — and this is both its strength (accessibility to Western readers) and its limitation (inevitable distortion in translation).