《黄帝内经·素问·至真要大论》
岐伯说：两阴之气都尽就称做幽；两阳之气相合就称为明。幽明的配合，成为寒暑的不同。
岐伯曰：两阴交尽故曰幽，两阳合明故曰明，幽明之配，寒暑之异也。
Qibo said: The qi of the two yin are exhausted is called obscure, the qi of the two yang combine is called bright. The correspondence of the obscure and the bright, becomes the differing cold and heat.