Motherhood
Rosa conceives, carries, and bears her daughter Magda under the most horrific of circumstances, but nevertheless loves her deeply. She keeps her alive under these impossible circumstances, neglects her own health to foster her child's, and makes every effort to remain alive herself so that Magda will. Rosa's love for her daughter is so much a part of her even though she barely gets to act like a mother under the conditions of the Holocaust. Her maternal feelings are elemental, unshakeable; Rosa is barely a woman anymore, barely a person—yet she is still a mother.
The Holocaust
It is impossible to capture the horrors of the Holocaust in a simple paragraph, or even a short story like Ozick's, but nonetheless certain realities about this period/policy are observable: Jews were treated as worse than animals, as vermin to be eradicated. They were stripped of their possessions and identities and, as the Nazis hoped, many of the vestiges of their humanity and dignity. They were corralled into ghettos first, then concentration camps which often turned into death camps. Conditions were horrific, death was ubiquitous, and those who lived suffered mental and physical traumas that can barely be articulated. Nevertheless, small moments of that humanity and dignity were possible, which is what we see with Rosa and Magda.
Resilience
The sheer litany of horrors expressed in this short story would be enough to justify the central character's impulse to give up, but Rosa refuses to give in to that. She keeps herself and her child alive—not to mention carrying and bearing that child. She doesn't do anything that could endanger Magda or herself as Magda's caregiver. And once Magda dies, she ignores the voices that urge her to go to Magda because "if she ran they would shoot, and if she tried to pick up the sticks of Magda's body they would shoot, and if she let the wolf's screech ascending now through the ladder of her skeleton break out, they would shoot." She will not give herself up as well; she will live to resist, she will live to record.
Nature
Nature seems to be far away from what Rosa, Stella, and the others in the concentration camps are experiencing. However, nature is evoked in subtle ways to allude to the power and dignity of the Jews even as they were utterly dehumanized. Magda is like a "squirrel in a nest, safe," with eyes like "blue tigers." When she dies she is like "a butterfly touching a silver vine." When Rosa is out in the yard she envisions "another life, of butterflies in summer. The light was placid, mellow. On the other side of the steel fence, far away, there were green meadows speckled with dandelions and deep-covered violets; beyond them, even farther, innocent tiger lilies." This dream is sustaining; it is what Magda will be part of.