Peripety, or peripeteia, is defined in the OED thus: "In classical tragedy (and hence in other forms of drama, fiction, etc.): a point in the plot at which a sudden reversal occurs. In extended use: a sudden or dramatic change; a crisis." Aristotle defines it more simply as change "from one state of things within the play to its opposite." Aristotle stresses the importance of peripeteia and discovery ("a change from ignorance to knowledge") in tragedies, especially in conjunction.