“In 18th century Paris the first thing the lieutenant of police did every morning upon reaching his desk was to inquire as to the price of a loaf of bread in the bakers’ shops of Paris. The price of the loaf would tell him whether he could expect a quiet day or should prepare for a day of unrest and violence in the streets. By the time the Bastille was stormed on July 14th, 1789, a loaf of bread cost the average laborer an entire month’s wages.”

http://www.environmentalleader.com/2012/04/25/cost-of-food-as-catalyst-for-change-cannot-be-ignored/