Ordo Templi Orientis is an occult secret society and hermetic magical organization founded at the beginning of the 20th century. The origins of O.T.O. can be traced back to the German-speaking occultists Carl Kellner, Theodor Reuss, Heinrich Klein, and Franz Hartmann. In its first incarnation, O.T.O. was intended to be modelled after and associated with European Freemasonry and as such in its early years only Freemasons could seek admittance.
Organisation of O.T.O., the diagram (from 1926) in German shows the organization's original structure.
A secret society is an organization about which the activities, events, inner functioning, or membership are concealed. The society may or may not attempt to conceal its existence. The term usually excludes covert groups, such as intelligence agencies or guerrilla warfare insurgencies, that hide their activities and memberships but maintain a public presence.
"Secret Society Buildings at Yale College" by Alice Donlevy c. 1880. Pictured are: Psi Upsilon (Beta chapter), 120 High Street. Left center: Skull and Bones (Russell Trust Association), 64 High Street. Right center: Delta Kappa Epsilon (Phi chapter), east side of York Street, south of Elm Street. Bottom: Scroll and Key (Kingsley Trust SSS Nonse Association), 490 College Street.
The Brethren of Sincerity) were a secret society of Muslim philosophers in Basra, Iraq, in the 9th or 10th century CE.
A Hongmen seal, 19th century
