“Second Variety,” Philip K. Dick, 1953 – A soldier discovers that his self-replicating, mechanical enemies have discovered a new, thoroughly disorienting form of camouflage—the imitation of human beings.
Comments: Online text at Project Gutenberg; Librivox recording also available. Themes include “performing human,” embodied identity, the arms race, nuclear war, replication/authenticity, and adaptation. Several aspects recall television’s re-imagined Battlestar Galactica; see also the Wikipedia review, which comments on similarities to the Terminator series. See a more detailed review, which discusses Dick’s use of empathy, spirituality, and anthropology, at Downcast Lids. The SF Site also offers a detailed review.
Dick’s comment on the story:
“‘My grand theme — who is human and who only appears (masquerading) as human? — emerges most fully. Unless we can individually and collectively be certain of the answer to this question, we face what is, in my view, the most serious problem possible. Without answering it adequately, we cannot even be certain of our own selves. I cannot even know myself, let alone you. So I keep working on this theme; to me nothing is as important a question. And the answer comes very hard.'” (Wikipedia, Second Variety)
Author: Wikipedia: “Philip Kindred Dick (December 16, 1928 – March 2, 1982) was an American novelist, short story writer and essayist whose published work is almost entirely in the science fiction genre. Dick explored sociological, political and metaphysical themes in novels dominated by monopolistic corporations, authoritarian governments, and altered states. In his later works Dick’s thematic focus strongly reflected his personal interest in metaphysics and theology.”