There are methods and schools, mostly taoist, which claim that the state of immortality is defined as a state of pure yang. A human is both yin & yang and has to get rid of all yin or change it to yang to become an immortal. Taichi is taoist and incorporates only the absorption of yang chi (heaven chi), at least according to Chen Man Ching. Gods, Buddhas and Immortals are considered as "heavenly" beings who are therefore pure yang.   Buddhist lineagues in China see yin chi as low or even dirty chi and as the chi of earth-bound gui (ghosts, devils).   Other schools and traditions like the Mo Pai teach the absorption of both yang chi from heaven and yin chi from earth and to fuse those together in the process of becoming immortal. John Chang confirms yin chi as the medium to get access to the ghost world.   Who's right? What method is better to become an immortal?