Meaning of "Not permitted to travel at night, but must arrive by dawn."

> 「不許夜行，投明須到」: "Fuku yakō, Tōmyō shudō," or "Bùxǔ yèxíng, tóumíng xū dào." Meaning "Not permitted to travel at night, but must arrive by dawn." This sentence appears in a kōan in *Blue Cliff Record*. > 趙州問投子：「大死底人卻活時如何？」投子云：「不許夜行，投明須到。」 > > Jōshū asked Tōsu, “What happens to a person who died a great death, > yet in the end returned to life?” Tōsu said, “They must not go by > night. They must arrive by dawn.” In light of the discussion on kṣaṇabhaṅga (“momentary decay”) and ēkacitta (“one unit of consciousness”) as in https://buddhism.stackexchange.com/q/55227/32114 What is Master Jōshū actually describing? There is also another kōan from *The Transmission of the Lamp*. > 問：「百了千當時如何？」師曰：「不許夜行，投明須到。」 > > Question: “What happens when everything is > in proper order?” The Master said, “They must not go by night. They > must arrive by dawn.” What is Master Fūketsu Enshō (風穴延沼) talking about here?