Marie Sinclair, Countess of Caithness

Marie Sinclair, Countess of Caithness (1830 – 2 November 1895), formerly Marie (or Maria) de Mariategui, was a British aristocrat of Spanish descent who married, as his second wife, James Sinclair, 14th Earl of Caithness. She is particularly remembered for her interest in spiritualism and Theosophy and her association with Helena Petrovna Blavatsky, whose occult successor she claimed to be.

Theosophical Society involvement

Lady Caithness became active in the Theosophical Society in New York in 1876, although her official date of joining was 1 February 1883, according to membership records at Adyar. At this time a wealthy dowager, she supported the Theosophical Society financially, and was crucial to the development of the Theosophical movement in France where she founded the "Société Théosophique d'Orient et d'Occident" on 28 June 1883 and served as its president. Among her writings was The Mystery of the Ages; Contained in the Secret Doctrine of All Religions, published in 1887.