Henry Maurice Dunlop Nicoll (19 July 1884 – 30 August 1953)[1] was a Scottish neurologist, psychiatrist, author and noted Fourth Way esoteric teacher.

[1] He served as ship's-surgeon for a brief stint to and from Buenos Aires before proceeding to tour the European hotbeds of the New Psychology, Vienna, Berlin, and finally, Zürich, where he met and became a close friend and colleague of C.G.

Following his service as a captain in the Royal Army Medical Corps during the First World War, where he first treated the wounded at the Gallipoli, Suvla Bay offensive, and after recovering from dysentery, he arrived with the 32nd Field Hospital of the 10th Irish division and did the same at the Siege of Kut, in Mesopotamia.

Nicoll is best known as a teacher and practitioner of the Fourth Way or esoteric Christianity of Gurdjieff and Ouspensky, but as his authorised biographer Beryl Pogson notes he privately read Swedenborg and the Gospels.

[6] His associated reflections on Neoplatonism, Gnosticism, Hermeticism, Alchemy, Sufism, Greek philosophy, Jakob Böhme, William Blake, along with variety of Indian and Chinese traditions (not to mention an assortment of individuals throughout history who have commented on consciousness) are as a whole present in Living Time and the Integration of the Life (completed by WWII but not published until 1952); yet both his published works and private papers have for the most part been publicly commented upon only infrequently.