The manas is a relay station

The manas is the relay station connecting the tathāgatagarbha with the mind consciousness, taking things from the tathāgatagarbha and handing them to the mind consciousness. The manas is not merely a relay station; it can itself remember the events it has experienced over countless kalpas. These events also exist as seeds in the tathāgatagarbha, and the manas is always in correspondence with the seeds, coordinated and consistent with them.

When a certain matter is needed, the manas prompts the mind consciousness to recall it; the manas then tosses the matter over to the mind consciousness, which brings it to mind and can even set about handling it.