the  kha’neqa’h  (monastery) of the  Molavieh  Order of  Sufis (founded by  Jalal al-Din Muhammad Rumi ), where Gurdjieff, Ouspensky and Thomas de Hartmann experienced the  sema  ceremony of The Whirling Dervishes . In Istanbul, Gurdjieff also met Captain  John G. Bennett , then head of British Military Intelligence in Constantinople .