Dread Of The Unknown

"With an effort, Boyd relaxed. He couldn't look at that small, big-headed figure in the armchair. The ancient human dread of the unknown was too strong in him."
-"Chain of Logic," 5, p. 64. (For full reference, see here.)

Dread is more than fear. We fear physical harm from an animal or human assailant whereas we dread the mere presence and even the existence of the eerie or uncanny. (See also The Alien As Threat.) At the same time, this figure in an armchair might also pose a real threat - to supersede humanity. This is a touch of horror fiction: horror can be fantasy (ghosts, demons etc), sf (aliens, mutants etc) or neither (cannibals, serial killers etc).

However, Poul Anderson's fiction is usually optimistic. By the end of the story, Boyd hopes that mutual understanding between humanity and the "big-headed figure" will lead to a "'...sane civilization...'" (p. 67)

Horror has approached and receded.