“The advice was practical — the transition from the settlement's ambient light (the oil lamps, the bioluminescent fungi that Trilochan cultivated along the walkways) to the perimeter's darkness required time, the eyes' photoreceptors shifting from cone-dominated daylight vision to rod-dominated night vision over a period of twenty to thirty minutes. During that transition, looking at the ground produced anxiety without information — the darkness was undifferentiated, the shadows meaningless, the mind filling the visual void with threats that the eyes couldn't confirm or deny.”