---"Ring around the Rosie"--refers to a red mark, supposedly the first sign of the plague ---"A pocket full of posies"-- refers to sachets of herbs carried to ward off infection ---"Ashes, ashes" --either a reference to the cremation of plague victims or to the words said in the funeral Mass..."Ashes to ashes, dust to dust." Sometimes line three is rendered as "Atischoo, atischoo"--sneezing, another sign of infection. ---"We all fall down." -- The Plague was not selective in its victims; both rich and poor, young and old, succumbed.
It was thought to do with the bubonic plague. People would get lesions, at first in the shape of reddish round spots or "ring around the rosies." The "pocket full of posies" is supposed to smell pretty and cover up the smell of disease. "Ashes" refers to the burning of corpses. "We all fall down" refers to the numbers of people who died. However, this "origin" has been refuted and is no longer widely held to be true.