I recently framed a rubbing I did 30 years ago of John Jack's gravestone and am also now curious about his past. I did the rubbing when I was a college student, probably in my sophmore year in 1972. I remember doing the rubbing on an outing with some girlfriends and we did it either at the old granary in Boston or in one of the cemetaries in Concord Mass. I still have friends in Concord, some of whom were probably there that day, and will contact them to see if they can confirm it the gravestone is in Concord. I can then probably get some info about the man...and you are right it is an incredible epitaph written before the independance of 1776 and 100 years before the civil war.