- structure. Nine personality types belong to Enneagram, and these types are displayed in a circle forming the unity.
- triad. The nine personality types could be divided in two axes: one axis belongs to what is known “the triad” (the distinction between: action/ cognition/ emotion), while the other axis has not yet a named (even if is operating with another distinction: inward/ outward/ both inward and outward)
- wing. Each type has two wings – that means each type has some characteristics borrowed from its neighboring types (one in the left and the other in its right). So, an individual could be a certain type with the characteristics of only one wing (even though the type has two wings)
- continuum of traits. Apart the two axes presented above (on the one hand the distinction action/ cognition/ emotion; and on the other hand the distinction inward/ outward/ both inward and outward), in Enneagram could be found a third axis: each type could “travel” along a continuum of healthy -> average -> unhealthy, and back again.
- direction of integration & direction of disintegration. So, a type could “travel” from healthy “station” to the unhealthy “station”, a process named “direction of disintegration” (this process is counter-clockwise direction). Or, the person could start his/ her trip from the unhealthy “station” and go back to the healthy “station”, a process named “direction of integration” (and this one is clockwise direction).
- tools. Don Richard Riso and his collaborators developed three tools: 1) QUEST (The Quick Enneagram Sorting Test – see for instance “The wisdom of Enneagram”, 1999), 2) TAS (The Type Attitude Sorter – presented in “Understanding the Enneagram”, 1990) and RHETI (Riso-Hudson Enneagram Type Indicator – detailed in “Discovering your personality type”, 1992)
Don Richard Riso & Russ Hudson (1999): “The wisdom of the Enneagram. The complete guide to psychological and spiritual growth for the nine personality types”, Bantam Books