Zhang Heng of the Eastern Han once described such a spectacle in "Western Capital Rhapsody": after a thunderclap that shook the heavens, a colossal beast eighty zhang long came winding onto the stage. Suddenly, a towering, precipitous sacred mountain appeared on its back, where bears and tigers fought each other while apes swung through the trees in pursuit. Then a great bird came staggering forth, followed by a white elephant with a hanging trunk, swaying as it approached as though it were pregnant and about to give birth to a calf. Next, a huge fish appeared; once people saw it clearly, it transformed into a dragon, twisting and coiling through the air. At that moment, the wondrous and auspicious Sarira Beast appeared. It opened its mouth and exhaled. When the breath dispersed, it became an immortal carriage drawn by four deer, its lingzhi-shaped canopy covered in flowers. Then there appeared toads and turtles, water people playing with snakes, and performers swallowing swords and breathing fire. Suddenly, a great flood sprang from the level ground, the water flowing into a river. In an instant, clouds and mist filled the square, changing appearances and splitting into forms in a fantastic display that left people utterly astonished.
Did dragons, Sarira Beasts, and water people truly exist in this world?
Even if they did, would they suddenly appear and disappear in the densely populated Western Capital?
The provincial graduate believed that what Zhang Heng had written about must have been a form of illusion, like a mirage over the sea—though many believed the "immortal mountains" seen in mirages truly existed.
Illusion arts had probably first come from India. The Biographies of Eminent Monks recorded that many eminent monks who came east to spread the Dharma could use such techniques. For instance, An Shigao had