《太平广记·卷四百二十四·龙七》
又能写符。先把符烧成灰，和以汤水，让病人吞下，不一会儿又吐出来，那符竟然象没烧过一样。
又能书符，先焚符为灰，和汤水，与人吞之，俄复吐出，其符宛然如不烧。
And write spirit symbols also. First he would burn the symbols to ashes, mix them in with soup, and have the patients swallow it, and soon after it would be thrown back up exactly as though it had not been burned. 