An English man on a walking holiday experiences a short time in another man’s future and struggles with the ethics of whether and how to deliver a warning to that other man.

Although the method of time travel is fantasy, the man’s struggles with the ethics of time travel put the story soundly in the realm of foundational science fiction.
Michael Main
He had been an eavesdropper, and had come upon private information of a secret kind that he had no right to make use of, even that good might come—even to save life.

Variants

(1)
  1. “Accessory Before the Fact” by Algernon Blackwood, in The Westminster Gazette, 23 February 1914.
  2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . written by Algernon Blackwood