A merchant tells several stories, including his own, about a gate in Baghdad that lets one visit, but not alter, the past and the future.
This is a fascinating and sometimes baroque take on time travel. Unlike most time travel stories, where the protagonists (intentionally or not) alter the present with their actions in the past, or change the course of history with their glimpse of the future, these show time as a closed system: one cannot change the events of the past, but instead past, present, and future are tightly fitted pieces of the same whole. Time travelers meet themselves, and the future and past selves’ retain the knowledge of their meetings, but they are unable to perform actions that might prevent the meetings. However, while events cannot be changed, interpretations of the past can, and therein lies the grace and redemption in this story.