Skt. Tathagatagarba] All beings have the Buddha nature. It is the base for Enlightenment. As long as a being is not enlightened, the Buddha nature is covered by veils. Such a being is called a "sentient being". When these veils are purified and the pure essence of Buddha nature is experienced, enlightenment is attained. Like milk already has the potential to become butter, every being has the potential to attain enlightenment. Buddha nature is identical with The Kayas.