"Oi Treis Ierarchai" (The Three Hierarchs) is a religious and philological society, founded in Volos in 1907. Its purpose was to provide a library and reading room to the town of Volos "for the spiritual development and moral and religious education of its members and society in general". In 1908 the Society acquired the library of the late monk Zosimas Esphigmenitis. The Library is currently open to researchers by appointment.