The Mental Factors Are the Aspects of the Mind King's Functioning.

The five universal mental factors (caittas) not only operate when thoughts arise, but also operate together with the eight consciousnesses at every instant and every moment, accompanying the eight consciousnesses without ever departing for even an instant. Whenever the eight consciousnesses appear, the five universal mental factors accompany and operate alongside them. As stated in the first volume of the Yogācārabhūmi-śāstra, the five universal mental factors are the attendants of the mind-kings (citta-kings): whenever the mind-kings operate, they take the five universal mental factors as their attendants; without the five universal mental factors, the mind-kings cannot operate.

Take the operation of the mental factor of attention (manaskāra): for example, before a consciousness seed is to arise, there must be a direction in which it arises, and the place where it will arise must be determined. For instance, if it is to arise upon the colorful appearance of a flower before one's eyes, the manas needs to discern the flower's colors; once the location of this dharma has been determined, the consciousness seed rushes forth and arises at the place of that flower's material sense-object (rūpa-viṣaya) in the supreme faculty (indriya); or it rushes toward the location of a certain sound, arising at the place where the sound's sense-object appears in the supreme faculty; or it arises at some other location among the six sense-objects that the manas wishes to discern. Therefore, before the consciousness seed arises there is attention (manaskāra); attention means having a direction of arising and a location of arising. The mental factor of attention begins to operate before the consciousness seed has arisen, and after the seed arises it must continue to operate without cease. The operational characteristics of the mental factors and the mind-kings merge together perfectly: the mental factors are the operational characteristics of the mind-kings. On the surface, what is manifested is the operational characteristic of the mental factors, yet hidden within it is the operational characteristic of the mind-king's consciousness seeds flowing forth. Although the two are consistent, each has its own operational characteristic.

The last of the five universal mental factors is the mental factor of volition (cetanā). The final function of the mental factor of volition is to act and create. Once the mental factor of volition has finished its creating, it is equivalent to the mind-king having finished its creating; the consciousness-mind then ceases or shifts its location, and the mental factors at that dharma-location likewise disappear. From this principle, the operational characteristics of the mind-kings and the mental factors are consistent: their operations are twisted together. The characteristic is manifested in the operational characteristic of the mental factors' operation, while hidden within it is the operational characteristic of the consciousness seeds flowing forth; they cannot be separated.

The Mental Factors Are the Mental Actions of the Mind-Kings

When the consciousness seeds flow out, they form the substance of the mind-kings. The substance of the mind-kings is pure, because the consciousness seeds are pure. The consciousness seeds have no defiled nature, nor any wholesome or unwholesome nature; but when they combine with the mental factors and operate in the form of mental factors, mental actions that are wholesome, unwholesome, or neither wholesome nor unwholesome appear. Therefore, the mental actions of the eight consciousness mind-kings and the mental factors are in fact one and the same: the mental factors are the mental actions of the mind-kings. When the eight consciousness mind-kings operate, they operate in the form of mental factors, especially in the form of the five universal mental factors.