The purpose of this book, clearly set forth in the first paragraph of the Introduction, is: "first, to ascertain what sources Shakespeare used for the plots of his plays; secondly, to analyse the use he made of them; and, thirdly, to give illustrations, necessarily selective, of the way in which his general reading is woven into the texture of his work".

For the most part, Professor Muir's arguments are not affected by the answer we give to the question: Who was Shakespeare?", but in the second paragraph he begs the question by saying that there is no real reason to doubt that Shakespeare (i.e., Shaksper) attended both a petty school and a grammar school, "as he somewhere acquired the equivalent knowledge"! The fact is that the book tells us a great deal about "'Shakespeare's" knowledge and nothing at all about Shaksper's. It thus provides us with a very useful measuring-rod by which to test the claims of the various candidates, beginning with Shaksper himself.

It soon becomes apparent that attendance at a grammar school is a quite inadequate explanation of the knowledge Shakespeare acquired. If not, strictly speaking, a scholar (and no one is more anxious than the scholars themselves to prove that he wasn't), he was certainly a prodigious reader, and his reading was not limited to his own language. Besides "a reasonable knowledge of Latin", which he might have acquired at a grammar school, and perhaps a slight knowledge of Greek, he had "some knowledge of French, Italian, and perhaps a smattering of Spanish". Though he never disdained the help of translations, he sometimes uses words which come closer to the original than any available translation, and in some cases, there was no available translation.

He did not rely upon a single source for each play, but often consulted several versions of the same story, or combined in a single plot different stories, taken from different sources, with no obvious connection between them. Sometimes he seems to have worked with a book open before him, and sometimes he drew upon a well-stored memory. That is to say, his reading was not always a means to an end, but an end in itself, of which he afterwards made use as occasion served. Professor Muir is not only concerned with the sources of Shakespeare's plots, but also with verbal echoes in the plays which betray their origin, or at least bear witness to the fact that one author borrowed from the other though, apart from dates, it is often impossible to say which was the debtor.

Those of us who believe that the real Shakespeare was the 17th Earl of Oxford (1550-1604) will naturally discount some of the alleged sources as post-Shakespearean imitations like the "Bad Quartos" of the plays, as, for instance, when we are told that Nashe's Pierce Penilesse had a "considerable influence" on Hamlet. Pierce Penilesse was not published till 1592—three years after Nashe's famous allusion to "whole Hamlets, I should says handfuls, of tragical speeches". This is generally taken as referring to the 'Ur-Hamlet" a hypothetical lost source-play, but if Nashe was already familiar with Shakespeare's Hamlet in 1589, it obviously follows that he borrowed from it in 1592. Again, for King Lear, Shakespeare is supposed to have used Holinshed's Chronicle, The Mirror for Magistrates, The Faerie Queen, Sidney's Arcadia, the anonymous chronicle play of King Leir and a book called The Declaration of Egregious Popishe Impostures, by Dr. Samuel Harsnett, Chaplain to the Bishop of London. But the last two may well have been later than Shakespeare's play. Leir was entered in the Stationers' Register in 1594 (unless this was Shakespeare's own version), but not published till 1605; and Harsnett's book, to which Professor Muir devotes nearly fourteen pages, was published in 1603, but deals with events which took place in 1585-6 and formed the subject of an enquiry before an Ecclesiastical Commission in 1598 and 1602, when certain priests were accused of sham exorcism. Shakespeare is supposed to have borrowed freely from this book, especially for the part of Edgar, masquerading as Poor Tom; but ones suspicions are aroused when Professor Muir says:

"One of the first things that is likely to strike a reader of Harsnett's Declaration, is his detailed and unclerical knowledge of the theatre"'.

and confirmed when he adds:

"Harsnett may have derived this knowledge, superfluous for a Bishop's chaplain, from his undergraduate days at Cambridge; he may have frequented the play house in London; but as Chaplain to the Bishop of London he had the job of licensing books for the press . . . and it happens that his publisher, James Roberts, had a number of plays in his list, including the Second Quarto of Hamlet".

Is it possible that Harsnett's description of events nearly twenty years old took colour from a stage performance, or a private reading of King Lear which, in its turn, may have owed something to those same events? The answer to that question depends upon the date of Shakespeare's play, but Harsnett's knowledge of the theatre is a strange coincidence.

A great deal has been written in recent years about the sources of individual plays, but this book is the first attempt at a much-needed synthesis, though it deals only with the comedies and tragedies. Professor Muir has wisely postponed a discussion of the History Plays for a second volume, "since there is so much disagreement about the materials on which Shakespeare worked". The disagreement is, of course, on the vital question of "Who borrowed from whom ?"—a question whose implications have not yet been fully realized.