We have a theory called the 'Six degrees of separation'. But facebook analytics show that it's just five degrees in reality.

Which tells us that the distance of introduction between any one person and the other person, is just 5 hops. Or simply put, For any two given set of people, Say you and I. The following will almost always hold true.
There will be a set of 5 people, let's call it S, which will hold 5 individuals : A, B, C, D and E, such that
I know A and A knows B and B knows C and C knows D and D knows E and E knows you; five hops. But it's always difficult to identify who they are.

Not an efficient plan but if we reached out to them first, E's persuasion might hold more power than any one of us individually or collectively.