"Lately I've been thinking a lot about the Turk", writes Adam Gopnik. He's talking - not of the Ottomans - but the famous chess playing machine constructed in the late 18th century.

A mechanical figure of a bearded man, dressed in Turkish clothing, appeared to be able to play a strong game of chess against a human opponent. It was - in fact - a mechanical illusion that allowed a human chess master hiding inside to operate the machine.

It was a sensation. But the players inside were nothing more than good chess players.

"We always over estimate the space between the uniquely good and the very good", Gopnik writes. "We worship one tennis player as uniquely gifted, failing to see that the runners-up, who we scoff at as perpetual losers, are themselves fantastically gifted and accomplished, that the inept footballer we whistle at in despair is a better football player than we have ever seen or ever will meet".

As some of the world's top chess players battle it out in London in the Candidates Tournament for the World Chess Championship, Adam Gopnik reflects on why we overrate masters and underrate mastery.