It is galling to know that, however unpleasant my review of Tate Britain's Blake 1809, it could never live up to the standards of bile set by the critic of The Examiner at the exhibition's first opening two centuries ago.

Of this, the only solo show William Blake had in his lifetime, Robert Hunt wrote: "The poor man fancies himself a great master, having painted a few wretched pictures, blotted and blurred and very badly drawn." The artist's accompanying Descriptive Catalogue, reprinted now by the Tate, was "a farrago of nonsense ... the wild effusions of a distempered brain". Warming to his theme, the vulpine Hunt concluded that Blake was "an unfortunate lunatic", and retired for the night a happy man. Not so William Blake, The Examiner's notice being the only one his show received.

So various questions spring to mind, the first being why Tate Britain has chosen to restage one of the greatest duds in the history of British art. The answer, of course, is that modern viewers will, as one, take sides with Blake against Hunt. In the 200 years that separate the first and second outings of this show, the unfortunate lunatic has entered the canon as a national treasure, a poet and visionary on a par with Milton and Turner.

This transformation is an object lesson in the fickleness of art history...