The following is simultaneously an essay in sociological theory, in cultural sociology, and in the empirical reconstruction of postwar Western history. Per theory, it introduces and specifies a model of cultural trauma - a model that combines a strong cultural program with concern for institutional and power effects - and applies it to large-scale collectivities over extended periods of time. Per cultural sociology, the essay demonstrates that even the most calamitous and biological of social facts - the prototypical evil of genocidal mass murder - can be understood only inside of symbolic codes and narratives; that these frames change substantially depending on social circumstances; and that this culture process is critical to establishing understandings of moral responsibility. Empirically, this essay documents, in social and cultural detail, using both secondary and primary sources, how it was that the `Holocaust' gradually became the dominant symbolic representation of evil in the late twentieth century, and what its consequences have been for the development of a supra-national moral universalism that may restrict genocidal acts in the future.