From 《
战国策·
赵策一》 (Strategies of the Warring States, Zhao). The assassin Yu Rang (
豫让), swearing to avenge his lord Zhi Bo after the house of Zhao destroyed him, declared 『
士为知己者死,
女为悦己者容』— 'a gentleman dies for the one who knows him; a woman makes herself beautiful for the one who delights in her.' He swallowed charcoal to ruin his voice and painted his skin with lacquer to disguise himself, pursuing the vendetta to his own death.