              That said, catharsis is undoubtedly a key concept in Aristotle’s Poetics, one which, along with imitation (mimêsis), has generated enormous  controversy.[26]   These controversies center around three poles of interpretation: the subject of catharsis, the matter of the catharsis, and the nature of catharsis. To illustrate what is meant:  on a naïve understanding of catharsis—which may be correct despite its naïveté—the audience (the subject) undergoes catharsis by having the emotions (the matter) of pity and fear it experiences purged (the nature). By varying just these three possibilities, scholars have produced a variety of interpretations—that it is the actors or even the plot of the tragedy which are the subjects of catharsis, that the purification is cognitive or structural rather than emotional, and that catharsis is purification rather than purgation. On this last contrast, just as we might purify blood by filtering it, rather than purging the body of blood by letting it, so we might refine our emotions, by cleansing them of their more unhealthy elements, rather than ridding ourselves of the emotions by purging them altogether. The difference is considerable, since on one view the emotions are regarded as in themselves destructive and so to be purged, while on the other, the emotions may be perfectly healthy, even though, like other psychological states, they may be improved by refinement. The immediate context of the Poetics does not by itself settle these disputes conclusively. 