Not all countries observe April Fools’ Day in the same way. In some places, it is one of the most light-hearted days of the year; in others, the day is not a joking matter.

Historians feel there is no definitive origin of April Fools’ Day, but the current thinking is that it may have began around 1582 in France with the reform of the calendar under Charles IX.

“The Gregorian calendar was introduced, and New Year’s Day was moved from between March 25 to April 1 (new year’s week) to January 1,” according to April Fools R Us, a site dedicated to fools and pranksters. With the earlier Julian calendar, the vernal equinox was March 21.

As noted earlier by IMT, France adopted the Gregorian calendar in 1564. In 1582, Pope Gregory XII made it official. Scotland held out on adopting the new calendar until 1660; and Germany, Denmark and Norway began using the Gregorian calendar in 1700.

At least two difficulties arise from the calendar-shift explanation:

1) It doesn’t fully account for the spread of April Fools’ Day to other European countries. England didn’t adopt the Gregorian calendar until 1752, for example, but April Fools’ Day was already well established there by that point.

2) We have no direct historical evidence for this explanation, only conjecture; and that conjecture appears to have been made more recently.

Others believe that the “holiday” began earlier, between 1508 and 1539, and that not only the French but the Dutch described April Fools’ jokes and the custom of making them on April 1.

(Other theories of origin here)

Another explanation of the origins is that the practice began during the reign of Constantine, when a group of court jesters and fools told the Roman emperor that they could do a better job of running the empire. Constantine, amused, allowed a jester named Kugel to be king for one day. Kugel passed an edict calling for absurdity on that day, and the custom became an annual event.

In France, the fool was called the poisson (“fish”) d’Avril (“of April”) because a young and na