About This Answer
Does the knowing, or mindfulness, cease at the death of an arahant? Ajahn Dtun explains that what ceases for an arahant are the kilesas; the knowing nature of the mind does not cease. Unenlightened beings, and those at every level of attainment, sotāpanna, sakadāgāmī, anāgāmī and those on the path to arahantship, all have this knowing, that which knows in the mind.
For an arahant, however, the knowing is now pure, with no kilesa in it. This purity is often called the Dhamma element, the basic pure knowing of the mind, and on the arahant's death it moves to a sphere exclusive to pure enlightened minds. For the unenlightened, doubt and speculation about this will never end; to really know the truth one must take the mind to arahantship and see for oneself.