A singular fatality has ruled the destiny of nearly all the most famous of all of the works of Leonardo da Vinci. Two of the three most important were never completed. Obstacles which arose during his life-time obliged him to leave them unfinished. These were the Sforza Monument and the Wall-painting of the Battle of Anghiari. The third–namely, the picture of the Last Supper at Milan–has suffered irremediable injury from both decay and the repeated restorations to which it was recklessly subjected during the XVIIth and XVIIIth centuries. Nevertheless, no other picture of the Renaissance has become so well known and popular through copies of every description.
— Excerpt from ‘The Notebooks of Leonardo Da Vinci’