The period assigned to Chang Kuo is the middle or close of the seventh to the middle of the eighth century A.D. He lived as a hermit on Chung-t’iao Shan, in the prefecture of P’ing-yang Fu in Shansi. The Emperors T’ai Tsung and Kao Tsung of the T’ang dynasty frequently invited him to Court, but he persistently refused to go. At last, pressed once more by the Empress Wu (A.D. 684–705), he consented to leave his retreat, but was struck down by death at the gate of the Temple of the Jealous Woman. His body began to decay and to be eaten by worms, when lo! he was seen again, alive and well, on the mountains of Hêng Chou in P’ing-yang Fu. He rode on a white mule, which carried him thousands of miles in a day, and which, when the journey was finished, he folded up like a sheet of paper and put away in his wallet. When he again required its services, he had only to spurt water upon the packet from his mouth and the animal at once assumed its proper shape. At all times he performed wonderful feats of necromancy, and declared that he had been Grand Minister to the Emperor Yao (2357–2255 B.C.) during a previous existence.
In the twenty-third year (A.D. 735) of the reign-period K’ai Yüan of the Emperor Hsüan Tsung of the T’ang dynasty, he was called to Lo-yang in Honan, and elected Chief of the Imperial Academy, with the honourable title of Very Perspicacious Teacher.
It was just at this time that the famous Taoist Yeh Fa-shan, thanks to his skill in necromancy, was in great favour at Court. The Emperor asked him who this Chang Kuo Lao (he usually has the epithet Lao, ‘old,’ added to his name) was. "I know," replied the magician; "but if I were to tell your Majesty I should fall dead at your feet, p. 295 so I dare not speak unless your Majesty will promise that you will go with bare feet and bare head to ask Chang Kuo to forgive you, in which case I should immediately revive." Hsüan Tsung having promised, Fa-shan then said: "Chang Kuo is a white spiritual bat which came out of primeval chaos." No sooner had he spoken than he dropped dead at the Emperor’s feet.
Hsüan Tsung, with bare head and feet, went to Chang Kuo as he had promised, and begged forgiveness for his indiscretion. The latter then sprinkled water on Fa-shan’s face and he revived. Soon after Chang fell sick and returned to die in the Hêng Chou Mountains during the period A.D. 742–746. When his disciples opened his tomb, they found it empty.
He is usually seen mounted on his white mule, sometimes facing its head, sometimes its tail. He carries a ph?nix-feather or a peach of immortality.
At his interviews with the Emperor Ming Huang in A.D. 723 (when he was alive still) Chang Kuo "entertained the Emperor with a variety of magical tricks, such as rendering himself invisible, drinking off a cup of aconite, and felling birds or flowers by pointing at them. He refused the hand of an imperial princess, and also declined to have his portrait placed in the Hall of Worthies."
A picture of Chang Kuo sitting on a donkey and offering a descendant to the newly married couple is often found in the nuptial chamber. It seems somewhat incongruous that an old ascetic should be associated with matrimonial happiness and the granting of offspring, but the explanation may possibly be connected with his performance of wonderful feats of necromancy, though he is said not to have given encouragement to others in these things during his lifetime.