What are the co-existent supports of each consciousness?

The co-existent support (sahabhū-āśraya) of the six consciousnesses is the manas; the co-existent support of the manas is the tathāgatagarbha. It is the tathāgatagarbha that directly gives birth to and sustains the manas, so that the manas can exist and operate continuously. The tathāgatagarbha directly gives birth to all dharmas, and the co-existent support of all dharmas is likewise the tathāgatagarbha; without the tathāgatagarbha, there would be no existence or operation of any dharma. However, the tathāgatagarbha must rely on the manas in order to function, to give birth to all dharmas, and to manifest the operation and characteristics of the tathāgatagarbha's activity. Therefore, the manas is the co-existent support for the tathāgatagarbha's operation of the various dharmas, but not the co-existent support for the tathāgatagarbha's birth, because the tathāgatagarbha originally exists and need not be born, and the manas cannot give birth to the tathāgatagarbha.