The three centres

The nine enneagram types are grouped into three triads, commonly called the instinctive (or body), feeling (or heart), and thinking (or head) centres, each containing three types and each associated with a characteristic emotion and a way of taking in the world. The body triad is associated with anger, the heart triad with shame, and the head triad with fear, as the underlying emotion each set of types must reckon with.

The triadic grouping is part of the personality typology developed from the mid-twentieth century, and it gives the nine types a deeper structure, sorting them by which centre of intelligence dominates.