Chen Huai'an transmigrated to become Li Jiancheng's advisor Chen Huai'an, and the start is the Xuanwu Gate? Intending to just survive by teaching, he instead relied on modern knowledge to help Li Shimin improve salt and iron, promote the imperial examination, provide disaster relief and quell chaos, forcefully transforming the Tang Dynasty into a "human ideal". Scientific salt production, movable-type printing, breaking the monopoly of aristocratic families—while others play power politics, he builds infrastructure. Not for power and status, but so that the common people of this prosperous age can live well.