E.M.W. Tillyard 
Shakespeare’s Problem Plays [PDF ebook] 

The Problem Plays-Hamlet, Troilus and Cressida, All’s Well That Ends Well and Measure for Measure-form a group distinguished by such common factors as a preoccupation with religious dogma and the problem of evil; an interest in human nature as it is, rather than with its latent capacities; and a strong contrast between the outlook of youth and age. Dr. Tillyard discusses these factors before tracing their effect in the individual plays, so that his study not only illumines each piece but also its neighbours. He thus succeeds in bringing these apparently disparate works into sharp focus, and establishes between them a mutually enlightening relationship.