Many scholars of Shakespeare at some point in their careers write a biography of their hero. Not many of them use it as an attempt to do the impossible, and define the peculiar “genius” that put their subject on top of the world.

Jonathan Bate describes his book as “a kind of biography”. In fact it is a twofold work, the first half an account of what we know or can profitably conjecture about the man, the second how and where his reputation has developed since. Underlying both parts is an impassioned need to find a good definition of his “genius”, what has given him his pre-eminent status. A strong part of that motive is Bate’s concern to rescue the canonical status of his works from what he calls the “New Iconoclasts”. In a modest aside, he employs a typically curt metaphor to explain how the obsessive attentions that Shakespeare gets “force us to scratch further at the matter of why he and not some other writer became the world genius of literature”.

The first half, “Origins”, gives a relatively orthodox account of Shakespeare’s life. Its sensible orthodoxy and Bate’s sensitive and easily-worn scholarship would make the book an ideally well-informed and smartly written candidate for any school library. Much better than most works of this kind, each chapter stands on its own feet yet develops out of its predecessor. Chapter 2, biography, is followed by Chapter 3, the other candidates for authorship, Chapter 4 sets up Marlowe as Shakespeare’s sibling rival. It is difficult to find fault with such a concise survey, rich in plausible speculation. The only complaint could be that there isn’t more of it.

For the identity of the young man of the sonnets, Bate unsurprisingly favours the Earl of Southampton, though he does adduce a couple of fresh and persuasive reasons for this well-matured preference. There are quite a few lively ideas in the other sections. The baffling begetter, “Mr W H”, for instance, he suggests may be no more mysterious than a compositor’s misreading of the original manuscript’s “Mr W S”. For the “Dark Lady” he has a wholly new candidate - the wife of John Florio, Italian secretary to the Earl of Southampton, who was the sister of Samuel Daniel, the poet. The novelty of this suggestion is hardly surprising since he has absolutely no new evidence to back it. He cannot get any nearer an explanation of her notorious “blackness” than that she came from Somerset and so might have been more sunburned than Elizabeth’s court ladies. Like so many details of the famously obscure “life”, it seems as likely a possibility as any other. Its tongue-in-cheek extravagance is a good counterpart to Bate’s severe treatment of the weirder biographical notions.The lunatic fringe of alternative claimants to authorship of the plays get a handsome rollicking.

In all this, the sonnets loom the largest of the written works. In an informative and easy flow of unavoidably cursory detailing, Bate throws out occasional flashes, like poet John Barnfield’ s love sonnets addressed to his “Gany-mede”. It is a splendidly readable account, carrying its learning lightly and using the texts (a term he scrupulous ly avoids) to amplify the fragments of hard information. The first half is a “life”, not a critique of the “works”. The closest he comes in this part to an account of the plays is his chapter on the sibling Marlowe’s influence, where his careful drawing of parallels leads him finally to canvass the possibility that Shakespeare made him the rival poet of the sonnets, dead though Marlowe most likely was by the time the young man of the sonnets started looking round for other admirers.

The second half of the book, “Effects”, is more ambitious and much more wide-ranging. Here defining the writer’s “genius” becomes the primary target, for all the expansive swings the account takes through English and European history, where painter Henry Fuseli and editor Thomas Bowdler rub shoulders with composers Verdi and Berlioz. Underneath this history of the way the genius’s reputation spread lies an urgent desire to rescue the idea of Shakespeare from the “New Iconoclasts”, who deny individual quality and see nothing better in studying Shakespeare than Bugs Bunny. Some of this Bate does rather rudimentarily, by using his history of the genius’s impact to show how readily the plays were taken up by left-wing as well as by right-wing critics. The fact that critic and essayist William Hazlitt, Victor Hugo and Australian novelist Frederic Manning took to Shakespeare as warmly as did Kenneth Baker shows how wrong it is to see the canon’s prime author as an agent of conservatism. Bate is scathing about the way “Shakespeare” was misused by Baker, Michael Portillo and the rest of the last government for what he calls “educational propaganda”, in their anxiety to promote the crude patriotism he labels “Arthur’s bosom”, after Mrs Quickly’s malapropism for Falstaff’s end. The “genius” of Shakespeare holds its appeal across almost the entire political spectrum.

There is a paradox here. In the end, Bate’s own definition of the “genius” of Shakespeare is based on how adaptable the plays are, and their capacity to give satisfaction to everyone. What we may see as a process mirroring in-built prejudices, Bate calls (referring to the sonnets) “the power to generate readings”. He finds his “omniShakespeare” best represented by Jorge Luis Borges’s allegory of the creator as actor, representing in his role-playing the world he finds around him. But there is surely much more to Shakespeare’s art than mirroring Elizabethan nature.

Andrew Gurr is professor of English at the University of Reading and chairman of the education committee at Shakespeare’s Globe, London