What Karmic Seeds Does the Ālayavijñāna Mind-Substance of an Arhat Contain?

An arhat abiding in nirvāṇa with remainder (sopadhiśeṣa-nirvāṇa) lives out his days in accord with conditions, without grasping at any dharma of the five-aggregate world, his mind empty and without self. The karmic seeds of the dharmas of the threefold world gradually fade away. Because there are no longer any karmic seeds of the threefold world, there will be no threefold world in future lives, much less a five-aggregate body born into the threefold world. If karmic seeds of the threefold world still remain in the arhat's eighth consciousness, those seeds will inevitably manifest in order to requite karmic actions, and there would then be no such state as nirvāṇa without remainder (anupadhiśeṣa-nirvāṇa).

However, after an arhat enters nirvāṇa without remainder, sooner or later he will reappear in the threefold world. This is because before entering nirvāṇa, the arhat had heard the Mahāyāna teachings and planted the seeds of the Mahāyāna dharma. When those seeds ripen, the eighth consciousness will output the seeds of consciousness for the manas, giving rise to the manas, entering the neutrino-body (antarā-bhava), taking rebirth once again, and cultivating and studying the Mahāyāna.

Karmic seeds correspond to the manas, and the manas corresponds to karmic seeds. If the manas does not grasp at the threefold world, then worldly karmic seeds cannot be retained; where there is grasping (upādāna), wholesome and unwholesome karma will continue to be created, karmic seeds will be left behind, and in future lives one will continue to take rebirth and transmigrate in accordance with those karmic seeds. When the manas does not grasp, the six consciousnesses create no karma; then there are no karmic seeds, and no karma needs to be undergone.