How were Shakespeare’s works preserved and passed down to us? It sounds like a rather dry and specialist question, but it is often important to know why the past looks the way it does, especially when considering books, in particular those that are so fundamental to the cultures in which we live.

In practical terms the 1623 folio is a vital resource, as it contains 18 plays, including Macbeth, Julius Caesar and The Tempest, that would otherwise have been lost. It is a sad truth that, as far as we can tell, a significant majority of Elizabethan and Jacobean plays disappeared, so Shakespeare's folio provides us with an idea of a world we could have lost.

The two actors who edited the plays, John Heminge and Henry Condell, commissioned a portrait of Shakespeare to accompany the text, a sign of his celebrity as well as the move from representing expensive books as high-status objects expressing the hard labour of dedicated scholarship.

It is hard to know whether Heminge and Condell, who knew and probably liked Shakespeare, always made accurate and fair choices. There has been much speculation about who Shakespeare collaborated with on a number of works: Thomas Nashe may have written large parts of Henry VI, Part One, and George Peele parts of Titus Andronicus; Thomas Middleton perhaps had a hand in Macbeth and All's Well That Ends Well; and John Fletcher definitely wrote Henry VIII with Shakespeare.

Writers were vitally important for Shakespeare, and he clearly worked well with other people, including actors such as William Kempe, who played the fool and Cordelia in King Lear, parts that appear to have been written for him.

All the plays, however, appear in the folio as Shakespeare’s work alone. Did the editors not know or care that Shakespeare often wrote with others, as did most early modern dramatists? Or was it just easier to lump all these plays together as the work of one man?

Whatever the truth behind these decisions, the choices of Heminge and Condell have helped to create the potent myth of Shakespeare the lone genius – and its obverse, Shakespeare the fraudulent frontman.

And why did they leave out certain plays? The most striking case is Pericles, which was ignored, unknown or failed to make the cut. It's a decision that has dogged the play ever since. Although it is the only play that I know in which a character hears the music of the spheres, the assumption made is that "its omission says something about its aesthetic worth", as Emma Smith, a professor at Oxford University, points out in The Making of Shakespeare's First Folio.

More puzzling still is the exclusion of the poems, as these were the most popular of Shakespeare's books. Venus and Adonis had been printed more than a dozen times when the folio came out, a true bestseller, in part because it was a racy pornographic comedy, more Jackie Collins than TS Eliot in places. Even so, poetry was far more respected as an art form than drama, so it would appear to be an odd choice to publish an expensive edition of Shakespeare's plays.

Scholars are divided about the commercial value of plays, whether they turned significant profits for publishers or were more of a risk, or even a liability.

Furthermore, although Shakespeare was celebrated in his lifetime as a major writer, albeit a bit saccharine for the most refined tastes, his stock seems to have fallen after his death, as his achievements were eclipsed by younger, more fashionable writers.

It was only later in the 17th century, in large part due to the publication of the folio, that he reached the pre-eminence that his brand has assumed ever afterwards.

Even so, Shakespeare was something of a magnet for publishers, and his work was clearly successful enough for keen-eyed entrepreneurs to spot a chance to make a fast buck.

In 1619, Thomas Pavier, who produced chapbooks and ballads as well as plays, published a series of quartos of works by Shakespeare.

Not only did he pioneer the publishing practice of "chunking", by gathering together the two parts of the Contention (Henry VI, Parts Two and Three in the folio) along with Pericles, but he published a number of works under Shakespeare's name that are not now thought to be by Shakespeare, notably A Yorkshire Tragedy and Sir John Oldcastle.

The former looks a bit like a Shakespearean tragedy (it is now thought to be by Middleton); the latter was a rival play to the two parts of Henry IV, which wanted to put the record straight about Sir John Oldcastle, the original Falstaff, and, surely, its unknown authors made use of a rivalry to generate interest.

Pavier perhaps believed that these were all Shakespearean works, or he may not have cared. Most interesting are the economic implications of his actions because “Pavier may have been inadvertently testing the market, or creating that market”.

The mainspring for one of the most influential books of all time would appear to have been the desire of a low-end publisher for a quick buck, which, in turn, might have been the principle motive for the publication of the folio itself. We should probably not be too concerned: the question of whether art functions best when it is half a trade is a hoary old cliche and an exam favourite.

The versions of plays included in the folio is a further matter worth considering. The editors argue in their prefatory letter that Shakespeare's spontaneous brilliance meant he never blotted a line, a description that is slightly more backhanded than many have assumed, and that has led to the assumption that he was a natural, untutored genius. But, of course, this is not true, and Shakespeare carefully revised plays such as the one now considered his masterpiece, King Lear.

The changes may have been because this bleak existential vision of pagan Britain bombed on stage. The folio printed the latest version, which suggests that “what Shakespeare’s theatre most valued was the up-to-date script, not the ‘original’ ”, an assumption at odds with much editorial practice now. Other plays were printed in sanitised versions as a matter of necessity. The Act to Restrain the Abuses of Players (1606) forbade the use of profanities and oaths on stage.

Othello appeared shorn of the bad language of its most foul-mouthed character, Iago, who regularly exclaims "Zounds!", a contraction of "God's wounds!", as part of his effort to represent himself as a bluff honest fellow who cannot help his rough edges. The 1622 quarto, almost certainly based on an original play script, restored the expletives.

Smith is a courteous and helpful guide who wears her considerable learning lightly in this enjoyable, well-conceived, well-written book. Readers who care about book history and bibliography will be much wiser by the end than at the beginning; the more sceptical will realise why they matter and how much they tell us.

Andrew Hadfield is professor of English at the University of Sussex. His most recent book is The Oxford Handbook of English Prose, 1500-1640