The Man Who Came Early — Poul Anderson

How rarely science-fiction writers succeed in creating a wholly alien culture may be judged from any adequate study of an earthly culture of a time or place which does not form part of our direct heritage. S.F's aliens may have pseudopods or supersdentific gadgets, but rarely so wholly different a frame of reference as man himself has achieved in other eras. Here F&SFs favorite Scandinavian skald takes us to Iceland near the end of the tenth century and convincingly depicts a truly "alien" way of life and teaches us the tragic truth that the role of a twentieth-century timetraveler to a "primitive" culture need not necessarily be that of Prometheus the Fire-Bringer.