of a mosaic:

          Nowadays, when an author dies, we can see clearly 
     that his own printed works standing in his bookcases are 
     those works which he regarded as completed and 
     finished, and that they are in the form in which he wished 
     to transmit them to posterity; his handwritten ‘papers’, 
     lying in his drawers, would obviously be regarded 
     differently; they were clearly not considered by him as 
     ultimately finished and done with. But in the days before 
     the invention of printing this distinction would not by any 
     means be so apparent. Nor could it be determined so 
     easily by others whether any particular piece written in 
     the dead author’s handwriting was of his own 
     composition or a copy made by him of somebody else’s 
     work. Here we have an obvious source of a great deal of