The Mind-Base Is the Driving Force That Manifests All Dharmas in the Three Realms

The mental faculty prompts the Tathāgatagarbha to generate the universe as the vessel-world, and it is also the karmic seeds that prompt the Tathāgatagarbha to bring forth the universe as the vessel-world. The mental faculty corresponds with karmic seeds, and the mental faculty represents karma, whether it is virtuous karma, non-virtuous karma, or neutral karma.

The arising of the universe as the vessel-world is prepared for the birth and existence of the five aggregates, and it is also a phenomenon of the three realms. Due to karmic seeds, when karmic conditions ripen, they prompt the Tathāgatagarbha to project the four great elements, forming the four elements. The Tathāgatagarbha of all sentient beings collectively manifests the vessel-world. Only after this formation can sentient beings be born. The purpose lies with the mental faculty. If the mental faculty has no purpose, and the karma of the threefold world ceases—like an Arhat entering Nirvāṇa without residue—then the three realms also cease to exist. 

The Twelve Links of Dependent Origination explain this principle: when karmic causes and conditions ripen, sentient beings are born; without the vessel-world, there would be no environment for existence, and the conditions for the birth of sentient beings would not ripen. This condition is also brought about by the mental faculty, which is the driving force for the manifestation of all phenomena in the threefold world.