For any number of reasons I’m interested in middlemen and brokerage.

Here are four ways that a broker might bring value to another group.

• Inform either side of interests or difficulties of the other.
• Import useful techniques, practices, tools.
• Draw analogies that the other group is blind to.
• Synthesis of techniques, practies, tools, ideas thru merging.

I very much doubt this is a usefully complete list. For example it doesn’t even include trading goods between the groups. But it’s a start.