A Third Type of Person

My son Tony & I went to a local expat pub for a quiz night.  

I was hoping to participate in the competition.

However, the teams had to have a minimum four members.  Tony & I were only two.  I asked him if we could ask some people to make a team.  "Let's just watch!" he said.  Looking around at the groups of people around us, I didn't see any hope in finding two people.  There were big groups that seemed insular and small groups too that seem cold and stand-offish. I resigned myself to my son's suggestion.

I complained to some about this afterwards.  They wondered why I didn't make the effort to find people.  The problem I later thought was there were two types of people at the pub:  those who I didn't know and those who I did, and there was no one of the third type.

The question now for me to answer is who and what are these third kind of people, and do they or have they ever existed.