The Enneagram of Personality (or simply the Enneagram, from the Greek words εννέα [ennea meaning "nine"] and γραμμα [gramma, meaning something "written" or "drawn"]) is a model of human personality which is principally used as a typology of nine interconnected personality types. Principally developed by Oscar Ichazo and Claudio Naranjo, it is also partly based on earlier teachings of G. I. Gurdjieff. The typology defines nine personality types (sometimes referred to as "enneatypes"), which are represented by the points of a geometric figure called an enneagram, which also indicates some of the connections between the types. There are different schools of thought among Enneagram theorists about some aspects of how it is understood.