Attending to Primo Levi's comment that The Periodic Table "goes beyond simple autobiography," I explore its mixtures of literary conventions and analyze the ways in which the action of writing constitutes a central trope that links Holocaust witnessing and narrative strategy. In this book, Primo Levi, writer, is inseparable from Primo Levi, Holocaust witness, and the discourses of science and of art are subtly intertwined and reciprocally illuminating. Levi's discussion of technological know-how and personal experience intertwine with the subtlety and rigor of a poem. Playing the building blocks of the scientific elements of the periodic table against the personal experience of the narrator, Levi constructs an interactive account. I discuss how Levi's friend Sandro, in the "Iron" chapter, and Rita, in "Zinc," helped his effort to resist fascist culture, including its propaganda. Levi seeks the "strenuous clarity" of physics and mathematics. As Levi's text unfolds, we discover the ways in which the effort to engage the cognitive dissonance of his situation helps him navigate the dire currents of the Holocaust. He connects the "small differences" of his chemical analysis to the consequences of a railroad's switch points. It is an analogy that leads to chaos theory, and Levi's discussion of the role Jews have played as life-giving impurities over and against fascist racialist ideology.