The ethical issues that scientific discoveries bring into sharp relief are at the thematic center of several stories in this collection. In “Understanding,” Leon, an unremarkable digital designer, receives doses of a newly developed drug, Hormone K, after nearly drowning. The drug, designed to regenerate damaged neurons, brings vast improvements to Leon’s intelligence, far beyond what should be humanly possible. The author utilizes this plot line to examine the consequences this scientific achievement might potentially have, aside from helping people with damaged nerves. As his understanding of reality grows, Leon becomes arrogant; he feels omnipotent and uses his new skills selfishly for his own benefit. Eventually, he comes across another person affected by the drug, Reynolds, who seemingly represents the other side of the spectrum: he dedicates his abilities to saving the world. At the same time, this big-picture worldview causes him to stop caring about individuals, whom he sees as necessary sacrifices in the battle for his goal. Both of these men exemplify the profound change scientific discovery can bring into a human life, and Chiang warns that some of them might not be so pleasant.

Similarly, in “Seventy-Two Letters,” Stratton achieves his advances in the field of nomenclature and self-replicating automata in the belief they will help make this technology cheaper to produce and therefore available to poorer families.