The five universal mental factors (pañca-sarvatraga) always operate together with the eight consciousnesses

The five universally active mental factors (pañca-sarvatraga-caitta) do not merely operate when thoughts arise; rather, they run together with the eight consciousnesses in every instant and every moment, accompanying the eight consciousnesses and never departing from them for even a moment. Whenever the eight consciousnesses appear, the five universally active mental factors accompany and operate alongside them. In Volume One of the Yogācārabhūmi-śāstra, Bodhisattva Maitreya states that the five universally active mental factors are the aids and companions of the mind-kings (citta-rāja): whenever a mind-king operates, it must rely on the five universally active mental factors as its aids and companions; without them, the mind-king cannot operate.

For example, before a seed of consciousness is to be born, there must first be a location for its birth—a place must be determined where it will arise. For instance, if it is to be born upon the flower's color seen by the eye, once the manas has determined that location, the seed of consciousness rushes forth and arises at the site of that flower's material sense-object within the supreme faculty; or it rushes toward the location of a certain sound, arising at the place where the auditory sense-object appears within the supreme faculty, or it arises at some other location that the manas wishes to discern. Therefore, before a seed of consciousness is born, there is first a mental engagement (manaskāra): mental engagement determines the direction of birth, the location of birth. Before the seed of consciousness has been born, the mental factor of mental engagement has already begun to operate. The operational characteristics (ākāra) of the mental factors and those of the mind-king merge together perfectly—their operational characteristics should be entirely identical. On the surface, what is manifested is the operational characteristic of the mental factors, while the operational characteristic of the mind-king's seeds of consciousness flowing forth is concealed within. Although the two are consistent, each has its own distinct operational characteristic.

Furthermore, the last of the five universally active mental factors is the mental factor of volition (cetanā). The final function of the volition mental factor is action and creation. Once the volition mental factor has completed its action, it is equivalent to the mind-king having completed its action; the consciousness-mind then ceases or shifts its location, and the mental factors likewise disappear. From this principle, the operational characteristics of the mind-king and the mental factors are consistent: their operations are twisted together as one. The operational characteristic is manifested in the operational characteristic of the mental factors' running, with the operational characteristic of the seeds of consciousness flowing forth concealed within—they are inseparable.