Cai Ze 蔡澤 was a high minister in the state of Qin 秦 during the Warring States period 戰國 (5th cent-221 BCE). He originated in Yan 燕 and wandered from court to court, but was nowhere received as a political advisor.ü>
He finally heard that Fan Ju 范雎, the Counsellor-in-chief of Qin, waged an unfortunate war against Zhao 趙. Fan Ju introduced him to the king, and he was appointed chief minister for visitors (keqing 客卿). Later on he succeeded Fan Ju in the post of chief advisor.
Cai Ze planned to extinguish the house of Zhou 周, but he was slandered by envious courtiers and thereupon remitted his official seal. He was, nevertheless, given the title of Lord of Gangcheng 剛成君. In this position he continued to serve the kings of Qin, for example, as chief diplomat during a mission to Yan.