Finding Paul Revere - why are matrices interesting?

I've been trying to work out why math is interesting, and in those efforts I am watching all of W. Gilbert Strang's MIT Linear algebra lectures.  While I am sure I am learning something, it's just not evidently clear why this is so important from the lectures, - I will try and work out what is important for everywoman or everyman in a later post. 

In the meantime Kieran Healy demonstrates the power of matrices, with an basic example from the NSA. The background is the public discussion in 2013 that the US government was collecting meta data on who was communicating with whom for as much of the 7+ billion people in the world as possible. In a post that should worry both todays patriots and the revolutionaries of 1772 he demonstrates how matrices can be used to find Paul Revere.

London, 1772.

I have been asked by my superiors to give a brief demonstration of the surprising effectiveness of even the simplest techniques of the new-fangled Social Networke Analysis in the pursuit of those who would seek to undermine the liberty enjoyed by His Majesty’s subjects. This is in connection with the discussion of the role of “metadata” in certain recent events and the assurances of various respectable parties that the government was merely “sifting through this so-called metadata” and that the “information acquired does not include the content of any communications”. I will show how we can use this “metadata” to find key persons involved in terrorist groups operating within the Colonies at the present time. I shall also endeavour to show how these methods work in what might be called a relational manner......follow link for more

To give away the ending, If you look in middle of the final graph - whom do you find? Also Kieran Healy posts is R code here: and you can paste the code from this page into R studio and make the graphs yourself (I still need to work out how to do it Pandas in python workbooks.)

Last note - my favorite line is "I have an upcoming EDWARDx talk about it." 4 years late it is clear that the TED talk format has become lets say - overdone?