Economic flow networks

For the purpose of later analysis, I'm going to mention abstract flow networks, then indicate that both the real economy and the financial economy are examples of abstract flow networks.

The real economy is a flow network involving goods, services, infrastructure and so on.

The control economy is a flow network of money.

An abstract flow network is a combination of:

• nodes
• directed edges (also known as directed flows)

These elements are connected as follows:

• every directed edge originates at a node and ends at a node. The starting and ending nodes may be the same.
• 
  

These can be . . .

I need a picture. How do I get pictures into this blog?