Literature Reference: 匪直也人，秉心塞渊，騋牝三千。——《诗经·国风·鄘风·定之方中》 Not only a man of integrity, but also one with a profound and steadfast heart, possessing three thousand mares. Source from 'Shijing·Guofeng·Yongfeng·Ding Zhi Fang Zhong'.
塞: The fortress, the frontier stronghold.
渊: It signifies being imbued with wisdom and imbued with a spirit of enterprise.
Meaning: A heart that is vast and profound, symbolizing depth and integrity.