One day, Ida comes home to find Frank in the backyard reading The Waste Land. He says he’s been listening to the birds and trying to understand what their song is saying. When Ida asks what he’s decided, he says they’re singing, “You’re just in the way.”
While Frank has been relatively staunch through the many disasters he’s suffered, without Elsa he’s slipped into depression for the first time. This is evidence both of the ferocity of his love for her and the fact that the effort of mental survival persists long after tangible challenges have ceased.
Ida is floored by this obvious display of depression. She feels the same horror and unreality she experienced when she watched the German tanks roll into Budapest. Right away, she goes inside and telephones Margaret.
For Ida, everything about Frank’s illness corresponds terrifyingly to her experiences during the war. But while she was helpless during the German invasion, now she knows exactly what to do; in this way, polio lets her recover some of the parental agency she lost during the war.