Katharsis is a beneficial transformation of painful emotions through absorbed contemplation of a powerfully moving work of art. The root meaning of "katharsis" in Greek is cleansing. The word can indicate the removal of impurities from, hence the amelioration of, any kind of substance. Before Aristotle, some philosophers had spoken (metaphorically) of psychological katharsis. Aristotle's student Aristoxenus claimed that Pythagoreans "achieved katharsis of the body through medicine, katharsis of the soul through music" (frag. 26). Plato sometimes employs the terminology of "katharsis" for philosophically extricating the soul or intellect from bodily concerns (e.g., Phaedo 67c; compare Sophist 226d–231b). But Aristotle was the first person to apply the term "katharsis" to the experience of tragedy.

The last clause of Aristotle's definition of tragedy in Poetics 6 describes tragedy as "accomplishing through pity and fear the katharsis of such emotions." No further reference to katharsis as the effect of tragedy...