How Can the Formless Tathāgatagarbha Be Perceived by the Conscious Mind?

The Tathāgatagarbha itself is formless, yet it possesses functioning marks, leaving traces that can be followed. These formless functioning marks do not require the Tathāgatagarbha to produce them through transformation, because the Tathāgatagarbha itself is the true Dharma. The true Dharma manifests without needing to be transformed. Therefore, it is said that the Tathāgatagarbha does not belong to the internal or external aspects of form. As long as the Tathāgatagarbha operates, it can be detected by the discerning sixth consciousness, which can grasp its formless, traceless traces.

The operation of the mental factors of the Tathāgatagarbha also has functioning marks. The sixth consciousness, transformed into wisdom, can directly observe the formless, traceless mode of operation of the Tathāgatagarbha's mental factors. Just as we can fully observe the force of the wind from the swaying of objects—the force of the wind being the formless, traceless mark—the sixth consciousness can directly observe it. Observing the Tathāgatagarbha follows the same principle.

However, there is a subtle difference between observing the operation of the Tathāgatagarbha's mental factors and observing the functioning marks of the Tathāgatagarbha.

The functioning marks observed by the consciousness are not produced by the Tathāgatagarbha through transformation, because the Tathāgatagarbha is real; only illusory dharmas need transformation. These functioning marks of the Tathāgatagarbha are also not the essence of the Tathāgatagarbha; they are marks manifested by the Tathāgatagarbha, being neither false nor true. For example, the reality and suchness of the Tathāgatagarbha are neither real nor unreal. They are also not substantial dharmas; the only substantial dharmas are the essence of the Tathāgatagarbha and the Buddha-nature.

In the non-abiding Nirvāṇa of Arhats, even the supreme wisdom like that of a Buddha cannot observe the essence of the Tathāgatagarbha, nor can it observe the functioning marks of its operation. Therefore, it is said that the Tathāgatagarbha is formless and invisible. Its functioning marks also manifest only based on the operation of the Tathāgatagarbha upon the illusory dharmas of the five aggregates; they are subsidiary functions of the Tathāgatagarbha, not entities.

The functioning marks of the Tathāgatagarbha are a type of dharma-dust. Regardless of the wisdom or cognition of the conscious mind, or whether it exists or not, this dharma-dust mark always exists. It is manifested during the operation of the Tathāgatagarbha, not produced through transformation. It has no seeds; thus, when consciousness lacks wisdom, it cannot recognize this dharma-dust mark. Furthermore, the operation of the mental factors of the Tathāgatagarbha is a type of dharma-dust mark. Regardless of whether consciousness exists or whether it has the wisdom to recognize it, this dharma-dust mark always exists. It is not produced by the Tathāgatagarbha through transformation; it is manifested by the Tathāgatagarbha itself during its operation.

It is similar to how a person walking, standing, sitting, or lying down under the sunlight during the day casts shadows. These shadows are not subjectively produced by the person. The principles are analogous but not entirely identical. Dharma that is too profound and subtle cannot be explained with complete clarity and detail; those with the wisdom to observe it can understand it intuitively.