Four increasingly intense levels of blissful awareness generated by the tummo inner heat causing bodhichitta energy-drops to fall from the crown chakra in the central channel of one's subtle body through the four progressively lower chakras. With each successive level of joy, the mind becomes subtler as one experiences the four voids. In complete stage mother anuttarayoga tantra practice, one applies the blissful awareness from each of the four joys to the cognition of voidness. The four joys are (1) joy (dga'-ba), (2) great joy (dga'-chen), (3) distinguished joy (khyad-dga') and (4) simultaneously arising joy (lhan-skyes dga'-ba).
Tibetan: དགའ་བ་བཞི། dga'-ba bzhi