In most forms of comedy, and certainly in the New Comedy with which Shakespeare was concerned, the emphasis is on moving towards a climax in which the end incorporates the beginning. Such a climax is a vision of deliverance or expanded energy and freedom. Frye draws on the Aristotelian notion of reversal, or , to analyse the three plays commonly known as the 'problem comedies': , , and , showing how they anticipate the romances of Shakespeare's final period.