《汉书·志·律历志上》
人统发生在寅初，曰光萌发出现黑色，到寅之中，日光渐亮成青光。
人统受之于寅初，日孽成而黑，至寅半，日生成而青。
The human unity occurs at the beginning of the hour of yin, the daylight sprouts and appears black, and at the middle of the hour of yin, the daylight gradually brightens into a blue light.