April Fools' Day is celebrated on April 1st every year, and it is one of the most light-hearted days of the year. Its origins are uncertain. Some see it as a celebration related to the turn of the seasons, while others believe it stems from the adoption of a new calendar.
The most widespread theory about the origin of April Fools' Day links the Gregorian calendar (格里高利历即阳历) reform. In 1582 France became the first country to switch from the Julian (儒略历) to the Gregorian calendar. This meant that the beginning of the year was moved from the end of March to January 1st. If someone failed to keep up with the change and continued to celebrate the New Year between March 25th and April 1st, various jokes would be played on him. Other people sent him on a "fool's errand" or tried to trick him into believing something false. Eventually, the practice spread throughout Europe.
There also have been quite a few attempts to provide mythological explanations for the rise of April Fools' Day.
One story dates back to Roman mythology, particularly the myth of Ceres (the Goddess of grain and the harvest) and Proserpina [the daughter of Jupiter (the king and ruler of the Olympian gods) and Ceres]. In Roman mythology Pluto, the God of the Dead, abducted Proserpina and brought her to live with him in the underworld. Proserpina called out to her mother Ceres for help, but Ceres, who could only hear the echo of her daughter's voice, searched in vain for Proserpina. The fruitless search of Ceres for her daughter was believed by some to have been the mythological antecedent of the fool's errands popular on April 1st.
It was once popular to christianize April Fool's Day by locating its origin in Biblical traditions. For instance, the tradition was attributed to Noah's mistake of sending a dove out from the ark before the flood waters had subsided, because sending the dove was on a fool's errand. A second story suggests that the day commemorates the time when Jesus was sent from Pilate to Herod and back again. The phrase "Sending a man from Pilate to Herod" (an old term for sending someone on a fool's errand) was often pointed to as proof of this origin theory.
In addition, anthropologists and cultural historians provide their own explanations for the rise of April Fools' Day. According to them, the celebration traces its roots back to festivals marking the springtime.
Spring is the time of year when the weather becomes fickle (变幻无常的), as if Nature is playing tricks on man, and festivals occurring during the spring traditionally mirrored this sense of whimsy (反复无常) and surprise. They often involved temporary inversions of the social order. Normal behavior no longer governed during the brief moment of transition as the old world died and the new cycle of seasons was born. Practical jokes, trickery, and the turning upside down of status expectations were all allowed.
OK, that's all, thank you.