You have probably heard the popular nursery rhyme, the original version of which is:
Ring a ring o’ roses
A pocket full of posies
We all fall down
This song refers to the occurrence and consequence of the great plague of London of 1665 which spread via fleas from diseased rats to the human population resulting in great loss of life. By the time the Plague reached epidemic proportions, the King and his court, as well as most clergy and physicians, had deserted London and left its poor to fend for themselves. Sir John Lawrence, Lord Mayor, remained to assume control of the city. Staying behind also were his friend and personal physician, Dr. Edward Harman; the Reverend Dr. Thomas Vincent, and a scientist named John Graunt, whose interest in statistics and trends helped to predict the spread of the disease.