The three teachings represent levels of spiritual attainment. In Cao Dai's teaching being a Buddha is the hardest to achieve. Cao Dai teaches that humans can develop into other beings. Humans can develop into: Thần (angel), Thánh (saint), Tiên (sage), and Phật (buddha). According to Cao Dai, everyone can turn into one of these beings. Angels, Saints, and Sages have extremely long lives in the realms of Heavens, but Buddhas are the only ones free from the cycle of birth and death.