In Chapter 16, Circe asks Odysseus why he went to war in the first place. His response strikes her as a paradox, and it also foreshadows what is ahead for Circe and her son:
He rubbed at his cheek. “Oh, because of a foolish oath I swore. I tried to get out of it. My son was a year old, and I still felt new-married. There would be other glories, I thought, and when Agamemnon’s man came to collect me I pretended to be mad. I went out naked and began plowing a winter field. He put my infant son in the blade’s path. I stopped, of course, and so I was collected with the rest.”
A bitter paradox, I thought: to keep his son he had to lose him.
Most people think of "keeping" a child as maintaining a presence in their life. Odysseus has decidedly not done this with Telemachus. Odysseus's professed commitment to his family has always puzzled readers of the ancient epic. On the one hand, he seems genuinely desperate to return to them. On the other hand, he abandoned them for the war. What's more, he takes careless and unnecessary detours that add years to his journey home. He is at least as committed to glory as he is to his family, even though these two commitments stand in direct opposition to one another.
In this exchange, Circe sympathizes with Odysseus and sees how his choice to go to war may have been, paradoxically, a choice for both glory and family. Odysseus reveals that he tried to "keep" Telemachus in his life for longer by feigning mental illness so that Agamemnon would not draft him. However, this well-intended plan backfired. The choice was no longer between keeping Telemachus or abandoning him, but rather between keeping him alive or killing him. In order to keep his son alive, Odysseus had to abandon him. Going to war was good for Odysseus's glory and bad for his family, but it was also the only way he could see to protect Telemachus.
The idea of "losing" a son in order to "keep" him comes back around later in the novel, when Telegonus gets old enough for a life beyond Aiaia. Circe is fiercely protective of her son because she knows that Athena wants to kill him. However, when Circe realizes that a teenage Telegonus will never forgive her if she does not let him leave the island, she finds it within herself to let him risk his life. Only by letting him go does she preserve a relationship with him. Later on, she again faces an impossible choice when Telegonus gets the opportunity to go with Athena to found Rome. She grieves to know that she will likely never see him again, but she says goodbye nonetheless because "keeping" him on Aiaia would be to lose her good relationship with him. Together, Odysseus and Circe demonstrate that "keeping" and "losing" can be two sides of the same coin.
In Chapter 27, as Circe prepares to give up her immortality, she uses a simile to help explain her paradoxical choice to be a mortal instead of a god:
My divinity shines in me like the last rays of the sun before they drown in the sea. I thought once that gods are the opposite of death, but I see now they are more dead than anything, for they are unchanging, and can hold nothing in their hands.
Circe compares her divinity (the quality that makes her a god) to a sunset. On the surface, this comparison appears to reinforce the idea that Circe's power comes from being a god. Plenty of people have remarked on the divine beauty in a Mediterranean sunset, but it is quite literally the essence of Helios within Circe that makes her a god. His powerful rays "shine" not only from the sky, but also from each of his children. Circe seems to be standing in awe of her own divine power just like someone else might stand in awe before an impressive sunset over the water.
However, the way Circe describes the sunset suggests that what she feels is more complicated than pure awe. The sun is not at its zenith, when it shines brightest and hottest. Rather, the "last rays of the sun" are "drown[ing] in the sea" inside of her. Given the way gods personify the natural world in Circe, this description of a sunset evokes the idea of a power struggle between gods. Helios's rays rise up and shine down on the sea every day, but every night Poseidon (the god of the sea) manages to drown them in his waves. This cycle of dominance between the sun and the sea is emblematic of the eternal tension between the Titans and the Olympians. Poseidon, brother to Zeus, is one of the original Olympians who overthrew Kronos and the Titans. Helios is a Titan who has conserved his own power by allying himself with Zeus, Poseidon, and the rest of the Olympians. Helios hopes that if Zeus stays complacent for long enough, the Titans might one day rise up again. The struggle between Helios and Poseidon every day as the sun sets and then rises represents the never-ending cycle of violence and fear into which the Titans and Olympians have locked themselves. Circe recognizes in this passage that the divinity within her is part and parcel of this eternal, exhausting battle for dominance.
Realizing that the gods will spend all their days for eternity fighting each other, Circe finally understands that she has been wrong about them all along: they are not living a life she envies. In fact, paradoxically, the immensity of their power—the fact that they can fight and fight and never die—makes them "more dead than anything" because they never have an impetus to grow, compromise, or appreciate what they have. They will always want more, and so they will never manage to simply be present with the life that is going on all around them. Circe chooses mortality not because she wants to die, but because she wants to live.