Artist Drawing from the Model is thought to be an allegory for the arts. The contrast between the laboriously worked background — where you can see every single line — and the loosely sketched, unfinished foreground, is stark. Since the printing process was so lengthy, the reason why Rembrandt agreed to produce the work remains a mystery. It may have been that he wanted to finish one section before the other. Others have speculated that the work was produced as a challenge for fine art students, who might have been asked to fill in the foreground in a way that complemented Rembrandt’s background. It may have been something of a novelty for students and collectors. (http://www.christies.com/features/Courtauld-unfinished-the-graft-behind-the-glitter-6295-1.aspx)