These are matters of astronomy and geography, lunar penalties and solar virtues, the four seasons' regulations, measures and numerical divisions, and yin-yang qi. These are the five elements' karmic deeds, the five administrative principles, the five musical tones in harmony, the five sounds according to their nature, the five flavors and their affairs, and the agreements on rewards and punishments. All of these have verifications; there are reasons for them being as they are. One follows them but cannot see their end, and one meets them but cannot see their beginning. Success in accomplishing tasks takes forms unknown to anyone. Maps cannot depict them, and names cannot fully express them.

A forced explanation would be: Vague and indistinct, yet there is an image within; indistinct and vague, yet there is something tangible within; profound and obscure, yet there is essence within. To thoroughly investigate truth and return to the formless: even ghosts, upon seeing it, cannot act as human agents. Therefore, sage persons value nocturnal travel.