During the (high) Middle Ages people worked very had and had little time for recreation. A workday lasted from sunrise till sundown. For some jobs, your shift could easily last much longer than that, 40-hour shift were not uncommon when working in the harbour. Only on sundays and holidays you had the day to yourself.
But sometimes during a particularly harsh winter the people had some reprieve from their hardships. It could get so cold the Maas river froze over, and work couldn’t continue.
At these times, the whole city came out on to the frozen river. Elegant ladies zoomed past shabby-clothed racing peasants. Children strapped on bones underneath their shoes and shuffled along behind chairs. Ornately carved sleighs were pulled by majestic horses adorned with jingling bells. Market stalls were set up in no time and games and dances were organized. The Maas tranformed in a happy winter carnaval.