Assume,  that you could write small letters on a surface by placing atoms next to each other in the shape of that letter. 

Now imagine that instead of writing the letters on a thick piece of material, you are writing them on a sheet of graphene which is only 1 carbon atom thick. 

When each sheet is filled, you stack a new sheet on top.

 How large of a volume (in cubic meters) would you need to fit all of the words of every book ever written by humans?

 Make your own calculation, and state all your assumptions.