This is also the name attributed to Hassan I Sabbah
the leader of the Ismaili
cult of Assassins
This came about because of Sabbah's fortress hideaway which was 'lost' in the mountains and denotes a relationship with the idea of the lone hermit, hence Old Man. From this 'Hermetic' position one can discern the Gnostic connection which plays such an important role in His operation and cultus.
Much of the philosophy expressed by the Ismailis is derived from the Secret Society known as the Brethren of Purity and their encyclopedia of knowledge; The Rasa'il.