After Cash finishes Addie's coffin, Vardaman is disturbed that she will be nailed up in it. Dewey Dell comforts Vardaman by telling him that they will get bananas for the trip to Jefferson, and Vardaman thinks about the toy red train-set behind glass in the Jefferson town toy store.
Vardaman's obsession with existence and how it can be expressed in language is momentarily quelled by the thought of his desires for bananas and toy-trains. This moment provides a glimpse into the way the Bundren family members think in a constant tug of war between familial obligation and individual concerns.
Vardaman notices that Anse walks around—and then corrects himself, "His shadow walks around." He then looks at Addie, about to be nailed in the coffin and claims "It was not my mother." He then connects this idea to the idea that the fish he caught was once alive, and is now chopped up, laying bleeding in the pan waiting to be "cooked and et." Vardaman continues to obsess over the distinction between "is" and "is not" and "was" and "was not."
Like Darl, Vardaman responds to Addie's death by grappling with the idea of how a live human body suddenly leaves the realm of existence upon the moment of death. He not only compares Addie to a fish, but obsesses over what it means to be "is" versus "is not."