The Knowable and Unknowable Grasping and Receiving of the 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 concealed that sentient beings cannot perceive it, it is called "unknowable"; yet the Buddhas and Bodhisattvas know it thoroughly and without doubt. For example, when a finger is severed, within a short period of time the finger can still be reattached and still retains its corresponding functions. During the time before it is reattached, one's own tathāgatagarbha is still upholding it—the severed finger still has neural activity, and its flesh has not become dead flesh. This sustaining 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 sustaining of the tathāgatagarbha; if the tathāgatagarbha no longer sustained them, not even dust would remain. At the time of attaining buddhahood, the Buddha clearly and fully knows the tathāgatagarbha's function of grasping and sustaining—there is not a single dharma that He does not know. Therefore, "unknowable" is said in relation to particular persons: for one who knows, it is knowable grasping-and-sustaining; only for one who does not know is it unknowable grasping-and-sustaining.