Which consciousness is the one that undergoes rebirth, transmigrating ceaselessly through the heavens, the underworld, and the human realm?

Question: Some say that the tathāgatagarbha, whose self-nature is pure and whose emptiness (śūnyatā) contains the seeds of the defiled seven consciousnesses, therefore drifts and turns along with the winds of karma, taking birth throughout the three realms and the six paths—sometimes being born in the heavens, or descending into the hells. Or being born in the human world, and because of denying the true Dharma, reappearing 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-nature, because the tathāgatagarbha is the substance of the mind, not a representation of the substance's nature. The nature is subordinate to the mind-substance in explaining the substance; it is not an entity. Only depending 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 follows karma to take birth; 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 seven great seeds, the seventh consciousness would be unable to take birth. Therefore, one cannot say that it is the tathāgatagarbha that takes birth in the cycle of rebirth in the heavens, underground, and in the human world; rather, it should be said that it is the seventh consciousness that continually takes birth, cycling through the heavens, underground, and the human world.