How we cite our quotes: (Chapter.Paragraph)
Quote #1
"You will find men like [Wainwright] in all the world's religions. They know that we represent reason and science, and, however confident they may be in their beliefs, they fear that we will overthrow their gods." (2.80)
Seems like a pretty cut and dry religion versus science theme, doesn't it? But if you read between the lines, you'll begin to see that its less a versus kind of dynamic and more a reworking and blending of the two.
Quote #2
[Stormgren] was honest enough to admit that, in the final analysis, his main motive was simple human curiosity. He had grown to know Karellen as a person, and he would never be satisfied until he had also discovered what kind of creature he might be. (3.10)
Many of the main characters in the novel—Stormgren, Rodricks, and Jeff Greggson—share the trait of curiosity. It's no coincidence that this trait is also the one that drives scientific discovery. It's as if the science in science fiction points toward a thematic and philosophical tone rather than the trappings of spaceships, ray guns, and alien invasions.
Quote #3
"We're pretty sure that Karellen can see and hear everything that happens on the surface of the Earth—but unless he uses magic, not science, he can't see underneath it." (3.54)
The third of Clarke's three laws reads: "Any sufficiently advanced technology is indistinguishable from magic" (source). While the Overlords' technology is said to be scientifically based, it might as well be magic for how we can wrap our puny human minds around how it works.
Quote #4
Though few realized it as yet, the fall of religion had been paralleled by a decline in science. There were plenty of technologists, but few original workers extending the frontiers of human knowledge. Curiosity remained, and the leisure to indulge in it, but the heart had been taken out of fundamental scientific research. (6.33)
This quote goes back to what we discussed in the first quote. You'd think the fall of religion would mean a rise in scientific philosophy, yet it doesn't work like that in the novel. Both human endeavors will suffer without support for curiosity about the unknown.
Quote #5
There was no point in developing rockets when the Overlords had infinitely superior means of propulsion, based on principles of which they had never given any hint. (8.11)
Think of it this way: Why bother studying for a test when the teacher will give you all the answers anyway? You'll pass the class, but will you really learn anything? When it comes to science, the Overlords gave humanity all the answers to the test, but mankind hasn't truly learned anything as a result.
Quote #6
[The ocean] was so alien, so remote from anything he had ever known that it set Jan's scalp crawling. And yet this was part of his own world… (11.32)
Jan's scalp tingling is that curious urge that sends him into the unknown to explore. Again, here we see that thread that connects the characters to the theme of science more so than all that awesome, futuristic technology (though awesome it is).
Quote #7
"I have made calculations based on what we know about the Stardrive, and using the firmly established results of the Relativity theory. From the viewpoint of the passengers on one of the Overlord ships, the journey to NGS 549672 will last not more than two months […]." (12.16)
The Overlords' science might as well be magic for how advanced it is, yet the novel has plenty of examples of real scientific laws and theories to keep it bound to reality. Here we have Einstein's Relativity theory, specifically drawing from what's called the Twin Paradox. Yes, that's a real thing, but we'll let Neil deGrasse Tyson take it from here.
Quote #8
Nothing in the realm of the supernatural, thought George, could be more eerie than the plain scientific fact that though almost ten years had passed since he had spoken to Jan, that now-far-distant voyager would have aged by only a few days.
The universe was vast, but that fact terrified him less than its mystery. (16.6-7)
One of the qualities that prevent George and his generation from ascending to the Overmind is this mentality, the fear of the unknown. Hard to explore those unknown, far reaches of the universe when the mere idea of doing so freaks you out.
Quote #9
"As you doubtless know, Sir, one of the great problems of our culture has been the dichotomy between art and science. I'd very much like to know your views on the matter. Do you subscribe to the view that all artists are abnormal?" (17.32)
Childhood's End is all about science—no question there—but it's got a lot of love for the arts, as well. See, the Overlords can pursue scientific inquiry and so can people, yet only humans can create works of art. As such, it's not the artist that is abnormal to the pure-reasoning mind of the Overlord, it's humanity. Period.