In everything pertaining to Nourishing Life, one should listen much but incorporate the essential, look wide but choose the best. One cannot rely on one's bias to a single practice. Moreover, the danger is that those who devote themselves to one of these practices trust only their discipline of choice. Those who know the arts of the Mysterious Woman and the Pure Woman say that one can transcend the world only through the arts of the bedchamber. Those who are expert in breathing say that one can extend the number of years only through circulation of breath. Those who know the methods for bending and stretching say that one can avoid aging only through daoyin. Those who know the methods based on herbs and plants say that one can surpass any limit only through medicines and pills. When the study of the Dao does not bear fruit, it is because of biases like these.