The Relationship between Mental Factors (caittas), Buddha-nature, and Tathāgatagarbha

Tathāgatagarbha is the mind-substance, the subject, the king; the five universal mental factors (caittas) are the subordinates, the objects, existing in dependence upon tathāgatagarbha; they are the followers. Where the king goes, the followers must follow. Tathāgatagarbha is that upon which they depend, and the mental factors are what depend on it—the relationship of master and follower is clearly established. It is just like sentient beings in the desire realm: the five aggregates or the seven consciousnesses are the master, or the manas is the master, and the body is the follower. Wherever the self of the five aggregates appears, the body must follow along. The relationship between the five universal mental factors and tathāgatagarbha is one layer more intimate, even more inseparable, than the relationship between Buddha-nature and tathāgatagarbha. There are times when Buddha-nature is separate, but there is never a time when the five universal mental factors are separate. Where there is tathāgatagarbha, there are certainly mental factors accompanying and operating; the mental factors and the conscious mind are never separated. It is just like a car that must have wheels, or a person who must have a body—it is the same principle.

The seeing of the mental factors and the seeing of Buddha-nature (seeing one's own nature) are two different modes of seeing, with different functions and operations. Buddha-nature is Buddha-nature, and the mental factors are mental factors; the two, from different aspects, cooperate with tathāgatagarbha in seeing the various dharmas and operating the various dharmas. The seeing of Buddha-nature requires certain conditions, such as light and darkness; in the state of nirvāṇa there are no marks of light and darkness, of arising and ceasing, nor are there any deluded dharmas, and therefore Buddha-nature does not function. But the operation of the mental factors requires no conditions at all; it never stops and is always functioning, never apart from tathāgatagarbha. Where there is tathāgatagarbha, there are certainly mental factors.