Lao Tzŭ said, “The wise man takes time by the forelock.” Han Fei Tzŭ adds, “One day the Court physician said to Duke Huan, ‘Your Grace is suffering from an affection of the muscular system. Take care, or it may become serious.’ ‘Oh no,’ replied the Duke, ‘I have nothing the matter with me;’ and when the physician was gone, he observed to his courtiers, ‘Doctors dearly love to treat patients who are not ill, and then make capital out of the cure.’ Ten days afterwards, the Court physician again remarked, ‘Your Grace has an affection of the flesh. Take care, or it may become serious.’ The Duke took no notice of this, but after ten days more the physician once more observed, ‘Your Grace has an affection of the viscera. Take care, or it may become serious.’ Again the Duke paid no heed; and ten days later, when the physician came, he simply looked at his royal patient, and departed without saying anything. The Duke sent some one to inquire what was the matter, and to him the physician said, ‘As long as the disease was in the muscles, it might have been met by fomentations and hot applications; when it was in the flesh, acupuncture might have been employed; and as long as it was in the viscera, cauterisation might have been tried; but now it is in the bones and marrow, and naught will avail.’ Five days later, the Duke felt pains all over his body, and sent to summon his physician; but the physician had fled, and the Duke died. So it is that the skilful doctor attacks disease while it is still in the muscles and easy to deal with.” * * * * * [Sidenote: HUAI-NAN TZŬ] To clear off finally this school of early Taoist writers, it will be necessary to admit here one whose life properly belongs to the next period. Liu An, a grandson of the founder of the Han dynasty, became Prince of Huai-nan, and it is as HUAI-NAN TZŬ, the Philosopher of that ilk, that he is known to the Chinese people. He wrote an esoteric work in twenty-one chapters, which we are supposed still to possess, besides many exoteric works, such as a treatise on alchemy, none of which are extant. It is fairly certain, however, that alchemy was not known to the Chinese until between two and three centuries later, when it was introduced from the West. As to the book which passes under his name, it is difficult to assign to it any exact date. Like the work of Lieh Tzŭ, it is interesting enough in itself; and what is more important, it marks the transition of the pure and simple Way of Lao Tzŭ, etherealised by Chuang Tzŭ, to the grosser beliefs of later ages in magicians and the elixir of life. Lao Tzŭ urged his fellow-mortals to guard their vitality by entering into harmony with their environment. Chuang Tzŭ added a motive, “to pass into the realm of the Infinite and make one’s final rest therein.” From which it is but a step to immortality and the elixir of life.