And so it was there by the flickering firelight in Purbeck Bay, John discovered the secret of the locket that would lead him to Blackbeard's treasure. For the words, "fourscore feet, deep well north" were the clues hidden in those verses from the bible. The days of our age are threescore years and ten, and though men be so strong that they come, to fourscore years, yet is their strength then..