For more than five centuries The Last Supper has been an artistic, religious and cultural icon. The art historian Kenneth Clark called it "the keystone of European art", and for a century after its creation it was regarded as nothing less than a miraculous image. And yet there is a very human story behind this artistic "miracle". Ross King"s Leonardo and the Last Supper is both a "biography" of one of the most famous works of art ever painted and a record of Leonardo da Vinci"s last five years in Milan.