Which consciousness takes rebirth in the endless cycle of saṃsāra in the heavens, the underworld, and the human realm?

Question: Some say that the tathāgatagarbha, whose self-nature is pure and which is emptiness (śūnyatā), contains the seeds of the defiled seven consciousnesses; therefore it drifts and turns along with the winds of karma, taking birth throughout the three realms and the six paths of rebirth—sometimes born in the heavens, or descending into the hells. Or born in the human world, and because of denying the true Dharma, it again appears in the hells. Can the tathāgatagarbha take birth? If it takes birth, does that not mean it is subject to arising and ceasing?

Answer: First, although the mind of the tathāgatagarbha is empty, it cannot be called emptiness (śūnyatā); it should be called the mind of emptiness (śūnyatā-citta), because the tathāgatagarbha is the substance of the mind, not a representation of the mind's nature. The nature is something subordinate to the mind-substance used to describe the substance; it is not an entity—only in dependence on the mind can the mind's nature exist.

Second, the tathāgatagarbha cannot take birth. Although the tathāgatagarbha contains the defiled karmic seeds of the seven consciousnesses, it is the seventh consciousness (manas) that takes birth in accordance with karma; the tathāgatagarbha merely follows the seventh consciousness in taking birth. When the seventh consciousness takes birth, it is the tathāgatagarbha that enables the seventh consciousness to take birth. Without the tathāgatagarbha's cooperation in outputting the karmic seeds and the seeds of the seven great elements, the seventh consciousness would be unable to take birth. Therefore one cannot say that it is the tathāgatagarbha that undergoes rebirth in the heavens, beneath the earth, and in the human world; rather, it should be said that it is the seventh consciousness that undergoes ceaseless rebirth and transmigration in the heavens, beneath the earth, and in the human world.