 Breathing practices exist in many varieties. The most common general terms are xingqi (“circulating breath”) and tuna (“exhaling [the old] and inhaling [the new breath]”). Particular practices include biqi (“retaining breath”), buqi (“spreading breath”), lianqi (“refining breath”), and tiaoqi (“harmonizing breath”). Another celebrated term is zhongxi (“breathing through the heels”), used in the Zhuangzi to designate the spontaneous breathing of the realized person, which does not stop at the lungs but circulates throughout the entire body (ch. 6; Watson 1968: 78). Two especially important practices are the ingestion of the “breaths” of the four directions (Raz 2013), and the so-called “embryonic breathing” (taixi), which purports to replicate the breathing of an embryo in its womb (Maspero 1981: 459–505).