Zaroff hums from madame butterfly, reads from marcus aurelius's writings, and smokes perfumed cigarettes. these are all examples of:

These are examples of juxtapositions. The barbarism of Zaroff is made even more jarring by his gentlemanly and pursuits that are referenced in his tastes. It is difficult to imagine someone as educated and cultured enough to enjoy Marcus Aurelius finding equal joy in his sadistic games.