It may not be too far-fetched to suspect Iain Sinclair's true vocation is biography. The nature of his quests sounds closer to Samuel Johnson, A.J.A. Symons or Richard Holmes' Footsteps than to most other contemporary literature. Sinclair's latest long book, Edge of the Orison, retraced John Clare's quixotic walk from Essex to London a hundred years later. Haunting the trails of predecessors and winding up the clocks of revered names are trademarks in the Sinclair venture: 'Initiation begins as an urge to remake whatever is admired.' The author of London Orbital has been cultivating an obsession with forgotten peers and building a peculiar Bibliotheca Abscondita of homage and allusion. Where other readers may detect a serious case of name-dropping, one is also invited to perceive generosity, genuine preoccupation with the other's fate. Sinclair's paying of respects functions as pedagogy; he is the kind of writer who opens up a world - a vocation, a trade - that lasts for the reader a lifetime. Some would condemn it as prestige through osmosis, a search for the blessings provided by contiguity, or the convenient symbiosis - parasitism - of a book dealer turned writer. Literature about literature conditions, like no other genre, the credentials a reader ought to bring as he knocks on the door. Seeing that much of what is printed today seems to ignore or disdain the fact that literature has been hanging around for centuries, a bit of concern ...