Monday, 26 August 2013
The first paragraph, dated AD 250, informs us of a turbine in the temple of Alexandria and of propellers on ships on an Earth-like planet elsewhere in the universe.
In the second paragraph, dated AD 1495, Leonardo da Vinci has made an airplane model but has no way to power it while beings on a planet of another star have built internal-combustion engines but have not thought of flying.
Next, in AD 1942, the Allies need to be able to detect submarines but are unable to develop ultrasonics while the people of Sumanor on Urish know about ultrasonics but "...had never heard of submarines." (p. 262)
Thus, each of these paragraphs presents a historical period with a science fictional perspective.
The action of the story starts in AD 2275 when, thanks to the null-null drive (we have met this before), interstellar journeys can be made at near light speed so that it becomes possible for rational species from different planetary systems to meet and to trade knowledge. No one can do everything well. Those who have developed science and technology in certain directions have not developed them in other directions but now all the discoveries can be exchanged and the first species to travel between stars in this volume of space, humanity, is able to profit by arranging the exchanges.
By coincidence, I had read Anderson's much earlier and very different story, "Captive of the Centaurianess," immediately before starting to read "Horse Trader." I therefore noticed that the Centaurianess is from Alpha Centauri A III and also that the new director of the Bureau of Intercultural Exchange, Technical Division, the "horse traders," was appointed because of his experience with the native civilization of Alpha Centauri A III. In the latter story, Anderson, perhaps deliberately, does not describe this Centaurian race, leaving us free to imagine that they are the large warrior women of the earlier story although this is extremely unlikely.