Ted Chiang's The Merchant & the Alchemist's Gate is a charming novella composed of a series of Arabian Nights-style stories-within-the-story.

In ancient Baghdad, a man is brought before the caliph to tell an astonishing tale that begins with a simple morning walk through the market. When Fuwaad ibn Abbas meets the merchant/alchemist Bashaarat, his life changes completely. For Bashaarat has invented a gate through which a person can travel into the past. To convince Fuwaad of the truth of his claims, Bashaarat relates stories of people who have traveled through his gate, which Fuwaad is in his turn relating to the caliph.

Fuwaad, of course, does decide to use Bashaarat's gate for himself, to prevent the horrible catastrophe that occurred in his own youth. But can the past really be changed, or is what has gone before fated?

The Merchant & the Alchemist's Gate is a pleasant fable, but I'm not sure, at a mere 64 pages, that it's worth the price.