Travel through time is an old fictional device, dating back to the mideighteenth century. Nineteenth-century novels of time travel such as Edward Bellamy's Looking Backward (1888) or Twain's A Connecticut Yankee in King Arthur's Court (1889) depended upon the hero falling asleep to change eras.

H. G. Wells's The Time Machine (1895) introduced the notion of constructinga machine that would allow a voyager to travel forward or backward. Much popular science fiction about timetravel relies upon the device of a timemachine to generate the story. Finney provides an interesting twist by assuming that time-travel is a product of deliberate imaginative effort. Si Morley experiences time not as a stream, but as shadow of the present given substance by sensation. Si moves into the past by recreating the sights, sounds, touches, smells, and tastes of 1882.