Understanding defining mentality (Buddhism)

In one striving for insight, this understanding is associated with defining the four immaterial aggregates.

On the Path of Purification of Hinayana Buddhism, panna (understanding) is considered as of one kind (monad), of two kinds (dyads), of three kinds (triads) or of four kinds (tetrads). There are five dyads, four triads and two tetrads. All have the characteristic of penetrating the individual essences or true nature of states (monad). In the third dyad, this is contrasted with understanding defining materiality.