The Caves of Steel trilogy, or the Robot series, by Isaac Asimov was one of my favorite works as a child. In fact, thanks to my mother, Isaac Asimov was one of my favorite authors as a child; I say that even though I hated Foundation. I loved Galactic Empire, and the Black Widower stories, and The Gods Themselves. I believe my introduction to him was my mother's copy of The Stars, Like Dust, a title which caught me with its beauty and punctuation at age nine.
I will tell you the three things that impressed me most about the Robot series, in which a human and android detective combine to solve murders while awesomely revealing and expounding to the reader sci-fi tropes of far-reaching societal consequence. (bam!) The first was the dark, warm, and hardly understood feels evoked by the romantic tension between Lije Bailey and Gladia in The Naked Sun, the second was the exploration of Earth public restroom etiquette in Caves of Steel (men never ever ever spoke to each other), and the third was the deleterious effect of the incredibly long lives of the Spacers on them individually and on their society.
Spacers, who were descended from the best Earth had to offer, and had departed purged of all disease, ruled every part of the galaxy they had explored. And they did not permit the short-lived and disease-ridden Earth-dwellers to leave their planet and pollute the cosmos. They lived for 300 or more years, feared death, lacked initiative, moved slowly, and craved safety.
Recall that the largest literary loom that loomed in my childhood was The Lord of the Rings. In that tapestry, the immortal elves were doomed to leave the world to men. They were the first children, and lived forever, but knew that the second children, doomed to die, had a fate beyond death that brought them closer to the Creator (although that is only explicitly stated in The Silmarillion, which I read years later). There is undoubtedly a bittersweetness to the elves' immortality, but that never robbed them of this: they blessed their world. The elves were crafters and gardeners and musicians and smiths and architects and poets. They made beauty appear everywhere they went.
I loved Lije Baley and R. Daneel Olivaw so much as a kid. I'm telling you, I read his adventures over and over again. But I knew, even as a child, what the difference between the worlds of Asimov and Tolkien were. There was no God in Asimov, and there was in Tolkien.
"If you were to die now," says Hans Fastolfe the Spacer to Lije Baley the Earther, "you would lose perhaps forty years of your life, probably less. If I were to die, I would lose a hundred fifty years, probably more." Spacers fear death, and the murder in their midst is too terrifying for them to contemplate.
Meanwhile, from the Wars of Beleriand to the dawning of the Age of Men, the elves, a noble race but not without their moral failings, not only continue to make beautiful things, but continue to lay down their lives for their world and for Men.
What's the difference between elves and Spacers? I'll tell you.
Elves know where they go when they die. They go to be in the light of Ilúvatar, who is a Christ-figure. In fact, they don't have to die to go there; they can sail there if they wish, though Men may not. The ones who stay love Creation, and will die for it, knowing what their blessed fate is.
C. S. Lewis feared that without the God of Christ we would become "men without chests". I believe we have become such men. But there is another organ missing. We don't live to 350 and own 10,000 robots, but we do live to 90 and own 3 robots. That apparently is enough.
We are the men without balls.