Take a person. Make the person maintain 1MB of data -- copy it, memorize it, something like that. Possibly understand it. Repeat for 5 million people. If 1MB i

Take a person. Make the person maintain 1MB of data -- copy it, memorize it, something like that. Possibly understand it. Repeat for 5 million people. If 1MB is too much, try 1KB, and repeat for 5 billion people. There should still be some people left for systems maintenance.