Four empties 四空

Four empties (Wyl. stong pa bzhi) — “The four empties are respectively termed the empty, the very empty, the great empty and the all-empty and are also called the mind of radiant white appearance, the mind of radiant red or orange increase, the mind of radiant black near-attainment and the mind of clear light.” See Daniel Cozort, Highest Yoga Tantra (Ithaca: Snow Lion, 1986), pp. 73–76. “These subtle types of consciousness are to be used to realize emptiness, but they are not themselves emptinesses, nor realizations of emptiness.” See Highest Yoga Tantra, p. 73.