An idea I've been musing on: is there a fundamental set of problems of humanity from which all economic activity is derived? For example:

"Shrink the world": couriers, seafarers, caravans, riders, roadbuilders, railroads, telegraphs, automobiles, steamships, dockworkers, truck drivers, aviation, telephones, email, social networking, videoconferencing.

"Organize labor": lords, finance, education, recruiting, HR, management, information systems, law, accounting.

"Keep us safe": militia, pikemen, shamans, legions, samurai, knights, musketeers, standing armies, chemists, doctors & nurses, the military/industrial complex.

"Food and shelter": self-explanatory.