For all their achievements ... for all their mastery of the physical universe, his people were no better than a tribe that had passed its whole existence upon some flat and dusty plain ... yet, Karellen knew, they would hold fast until the end: they would await without despair whatever destiny was theirs. They would serve the Overmind because they had no choice, but even in that service would not lose their souls.
This quote is from the end of Chapter 24, as Karellen watches the end of Earth. It gives an almost noble and spiritual coda to the plight of the Overlords, and also to that of humanity. There is an implication that in the process of joining the Overmind, the children of the last generation of humanity "lost their souls," whereas the individualistic Overlords still retain theirs. While Karellen may feel a sadness that his race is incapable of making the same leap that he has seen so many other races make, it is debatable whether Karellen wishes that the Overlords could join the Overmind in particular. The Overlords may hope to discover the Overmind's secrets and perhaps pose a challenge to it, or find a way to make the leap themselves into some higher form, without the Overmind's help.
Regardless of Karellen's intentions, there is a certain tragic, admirable nobility in the plight of the Overlords, and it is questionable who is to be admired: the humans who lose their individuality in the Overmind, or the Overlords, who live on to struggle against their own doubts, passions, and each other.