Why do critics and audiences feel that there is something ‘different’ about the plays that Shakespeare wrote after 1603? Scholars have for years focused on Shakespeare's later works as ‘Jacobean’ because of James I's accession to the throne in 1603. The plays – in the darkness of their comedy and in the general pessimism of the largely tragic period that followed – have been seen to mirror the despair and unease of an England that had lost its queen and had been plunged into the uncertainty that is inevitably part of a transition in power. More recently it has been argued that other crucial factors coincided with the change in regime. Shakespeare's interest in judicial rhetoric, the personnel changes in his own acting company, and his performances at court – all these helped shape such diverse and troubling plays as Measure for Measure, King Lear, and The Tempest.

But 1603 was also the year in which John Florio published his widely read translation of Montaigne's essays, which Shakespeare undoubtedly knew and used as he constructed phrases, speeches, and perhaps the thematic universe of whole plays.

In this book I contend that Shakespeare's reading of Montaigne is an under-recognised driving force in the development of his later work, from the choice of specific words to the employment of whole patterns of thought. Montaigne and Shakespeare share similar approaches to ideas of knowing, being, and aesthetic form, what John O'Brien has called ‘an esthetics of non finito and an ontology of incompleteness’. Theirs is a world of doubt, contingency, uncertainty, and mutability – in which receptivity to new ideas and new, more ‘open’ methods of literary composition feature strongly. Both authors dedicate themselves to exploring instabilities of self, knowledge, and form in disjunctive ways that stress interruption, fracture, and unexpected alternatives to conventional wisdom.

This quest to probe the instabilities of self, knowing, and world takes, for both writers, the form of ‘essays’. Although writing in a different genre, Shakespeare essays the Essais.