“Nature abhors a vacuum.” – Francois Rabelais
Indeed, it does. Things and people are brought together faster than water fills a vessel. We are by nature bound to be close.
Daily life drives us to people of all walks for support in terms of emotion, spirit, finance, and all the other aspects of living. We need to be close to them because they have something we need or, at least, want.
That closeness, that proximity, breeds connections, dependencies, and dependencies upon those until we find ourselves inside a network which we can barely comprehend, let alone master. This was the main takeaway (although extended) I had from reading “The World Is Flat.”
Trust is required for us to move from needing or wanting something to having it. But, as the old saying goes, no risk no reward. In pursuing wants and needs we must rely on others to live up to their word and our expectations. How can we be sure they will?
Some people have done their homework on the topic, and the results look like this:

I encourage you to take some time to read the detail and consider how you might use this to improve you understanding of your current relationships. There is a 4 minute video which nicely explains the concept.
Taking the equation as it is works well enough in certain contexts.