Reviewed by Robert Carver YALE UNIVERSITY PRESS, 288pp, £18.99Tablet bookshop price £17.10             Tel 01420 592974Even during his lifetime (1865-1959) the art critic, aesthete and picture entrepreneur Bernard Berenson suffered a catastrophic loss of prestige after it was revealed he had a secret agreement with picture dealer Joseph Duveen to “authenticate” Old Masters for a commission of 25 per cent of their sale price. After Berenson’s death, Colin Simpson’s Artful Partners: Bernard Berenson and Joseph Duveen nailed Berenson’s reputation in its coffin: while claiming to live on a higher plane morally and aesthetically, Berenson deliberately misattributed and falsified Old Masters fo