The Knowable and Unknowable Appropriations of Tathāgatagarbha

The unknowable grasping-and-sustaining of the tathāgatagarbha is its function of upholding all dharmas of the five aggregates and the eighteen realms. Because it is so hidden, sentient beings cannot perceive it, and thus it is called unknowable; yet the Buddhas and Bodhisattvas know it deeply and without doubt. For example, when a finger is severed, within a short period of time the finger can still be reattached, and the finger still retains its corresponding functions. During the period before it is reattached, one's own tathāgatagarbha is still upholding it; the severed finger still has neural activity, and the flesh has not become dead flesh. This upholding function is precisely the unknowable grasping-and-sustaining of the tathāgatagarbha.

If one comes to know this function of the tathāgatagarbha, it becomes the knowable grasping-and-sustaining of the tathāgatagarbha. That bones in a grave do not decay is all due to the upholding of the tathāgatagarbha; if the tathāgatagarbha no longer upholds them, not even dust would remain. At the time of attaining Buddhahood, the Buddha clearly and fully knows the grasping-and-sustaining function of the tathāgatagarbha, and there is not a single dharma that He does not know. Therefore, "unknowable" depends on to whom it is spoken: to one who knows, it is knowable grasping-and-sustaining; only to one who does not know is it unknowable grasping-and-sustaining.