《论衡·卷六·龙虚篇》
豫让吞下木炭，用漆涂身变得像得了麻风病一样，使人无法识别他的形体。
豫让吞炭，漆身为厉，人不识其形。
Yu Rang swallowed charcoal, applied lacquer on his body, and disguised himself as a person with leprosy, making it impossible for people to recognize his form.