Guiguzi or the Master of Ghost Valley; a mysterious philosopher from the Warring States period who founded the School of Diplomacy and was said to be the teacher of the strategists 苏秦 sū​qín and 张仪 zhāng​yí

The classic text attributed to Guiguzi which details the art of persuasion, diplomacy, and political strategy used during the Warring States period; also known as 捭阖策 bǎi​hé​cè