The Enneagram symbol is best known as representing a system of nine personality types. However, the earliest recorded use of the symbol comes from G.I. Gurdjieff and his students. This earlier use had nothing to do with personality types but was instead applied to understanding universal processes. Speculation has elements of the symbol dating to ancient times but there are no written records before Gurdjieff that produce a symbol looking like today's popularized Enneagram.
With each personality type represented by a number of the symbol (i.e., personality types 1 through 9), the types use the symbol primarily in two ways: 1) the relationship of the numbers to each other around the circle (e.g., centers of intelligence, wings, etc.) and 2) the relationship of the numbers to each other as indicated by the inner lines (e.g., stress/security points, directions of integration/disintegration, etc.).
There are four sets of triads typically used with the Enneagram symbol for the types. Each set of triads groups three types into three groups in a consistent way (usually centered around points 3, 6, and 9).
The first set of triads are grouped as 891, 234, and 567. This triad is used by most authors to describe the Centers of Intelligence.
The second set of triads are grouped as 792, 135, and 468. An example of this triad applied are the Harmonics Groups as used by the Enneagram Institute.
The third set of triads are grouped as 369, 147, and 258. Two examples of this triad in use can be seen in The Enneagram Institute's Object Relations Groups and the Harmony Triads as used by David Daniels. The Enneagram Attention approach goes one step further to actually use this set of triads to replace the traditional inner lines.
The fourth set of triads are grouped as 126, 459, and 783. This triad is most often used with Karen Horney's interpersonal coping types.
The two numbers on either side of a given number indicate the wing types (i.e., the wings for type 9 are types 8 and 1, the wings for type 1 are types 9 and 2, etc.).
The inner lines are sometimes used with the types to indicate a movement or connection from one type to the two other types indicated by the lines (i.e., 9 connecting to 3 and 6, 1 connecting to 4 and 7, etc.).
The inner lines consist of two separate patterns:
- the hexad connecting points 1, 4, 2, 8, 5, and 7
- the triangle connecting points 9, 3, and 6
The arrows and lines of the hexad indicate the law of 7, which comes from the Gurdjieff tradition. This pattern can found by dividing 7 by any number between 1 and 6:
- 1/7 = the repeating decimal number .142857....
- 2/7 = the repeating decimal number .285714....
- 3/7 = the repeating decimal number .428571....
- 4/7 = the repeating decimal number .571428....
- 5/7 = the repeating decimal number .714285....
- 6/7 = the repeating decimal number .857142....
The triangle implies the law of 3, which also comes from the Gurdjieff tradition.
The numbers indicated by the triangle (9, 3, 6) have sometimes been referred to as the center or balance points by the personality type system because they lie in the middle of the triads (specifically the centers of intelligence).