Friday, the president started off his NSA reform speech with a reference to Paul Revere and the Sons of Liberty, saying:  At the dawn of our Republic, a small, secret surveillance committee borne out of the “The Sons of Liberty” was established in Boston. The group’s members included Paul Revere, and at night they would patrol the streets, reporting back any signs that the British were preparing raids against America’s early Patriots.  But if the British Redcoats had access to the type of metadata and processing power the NSA does today, Revere probably would have been caught before he could go on his legendary midnight ride. In fact, even without cellphones, just by sifting through the memberships of social clubs at the time it would have been possible to use relationships to identify the key people involved in groups like the Sons of Liberty -- who surely would have been considered "terrorists" by the British Crown at the time.  Kieran Healy, a sociology professor at Duke University, wrote up an excellent, fictional, narrative version of how this could be done by examining information about memberships in various social clubs -- complete with privacy assurances.  Rest assured that we only collected metadata on these people, and no actual conversations were recorded or meetings transcribed. All I know is whether someone was a member of an organization or not. Surely this is but a small encroachment on the freedom of the Crown’s subjects.  By mapping individuals known to be involved in patriot-cause connected groups, you get this visual representation of the social connections:  And who is dead in the middle of this?  As Healy notes, this map wouldn't have told British intelligence anything about "his conversations, or his habits or beliefs, his writings (if he has any) or his personal life." But it would have surely made them give him a second look, and placed him near the top of their lists of suspected "terrorists."
The president just praised the intelligence gathering skills of Paul Revere. But if Redcoats had the ability to parse metadata, they probably would have caught him.