1.AprilFools'DayorAllFools'Day,thoughnotaholidayinitsownright,isanotabledaycelebratedinmanycountriesonApril1.Thedayismarkedbythecommissionofhoaxesandotherpracticaljokesofvaryingsophisticationonfriendsandneighbors,orsendingthemonfools'errands,theaimofwhichistoembarrassthegullible.Insomecountries,AprilFools'jokes(alsocalled"AprilFools")areonlymadebeforemidday.[1]ItisalsowidelycelebratedontheInternet.

　　2.Origin

　　Theoriginofthiscustomhasbeenmuchdisputed.Manytheorieshavebeensuggested.

　　Whatseemscertainisthatitisinsomewayorotherarelicofthoseonceuniversalfestivitiesheldatthevernalequinox,which,beginningonoldNewYear'sDay,the25thofMarch,endedonthe1stofApril.

　　IthasbeensuggestedthatEuropederiveditsApril-foolingfromtheFrench[2].FrancewasoneofthefirstnationstomakeJanuary1officiallyNewYear'sDay(whichwasalreadycelebratedbymany),bydecreeofCharlesIX.Thiswasin1564,evenbeforetheadoptionoftheGregoriancalendar(SeeJulianstartoftheyear).ThustheNewYear'sgiftsandvisitsoffelicitationwhichhadbeenthefeatureofthe1stofAprilbecameassociatedwiththefirstdayofJanuary,andthosewhodislikedordidnothearaboutthechangewerefairgameforthosewitswhoamusedthemselvesbysendingmockpresentsandpayingcallsofpretendedceremonyonthe1stofApril.FrenchandDutchreferencesfrom1508and1539respectivelydescribeAprilFools'DayjokesandthecustomofmakingthemonthefirstofApril.

　　Thoughthe1stofAprilappearstohavebeenancientlyobservedinGreatBritainasageneralfestival,itwasapparentlynotuntilthebeginningofthe18thcenturythatthemakingofApril-foolswasacommoncustom.InScotlandthecustomwasknownas"huntingthegowk,"i.e.thecuckoo,andApril-foolswere"April-gowks,"thecuckoobeingthere,asitisinmostlands,atermofcontempt.InFrancethepersonfooledisknownaspoissond'avril.ThishasbeenexplainedfromtheassociationofideasarisingfromthefactthatinAprilthesunquitsthezodiacalsignofthefish.AfarmorenaturalexplanationwouldseemtobethattheAprilfishwouldbeayoungfishandthereforeeasilycaught.

　　TheDutchcelebratethe1stofAprilforotherreasons.In1572,theNetherlandswereruledbySpain'sKingPhilipII.RoamingtheregionwereDutchrebelswhocalledthemselvesGeuzen,aftertheFrench"gueux",meaningbeggars.On1April,1572,theGeuzenseizedthesmallcoastaltownofDenBriel.ThiseventwasalsothestartofthegeneralcivilrisingagainsttheSpanishinothercitiesintheNetherlands.TheDukeofAlba,commanderoftheSpanisharmycouldnotpreventtheuprising.BrilistheDutchwordforglasses,soon1April,1572,"Albalosthisglasses".DutchpeoplefindthisjokesohilarioustheystillcommemoratethefirstofApril.

　　TheFrenchtraditionallycelebratedthisholidaybyplacingadeadfishonthebackoffriends.Todaythefishissubstitutedbyafloppykerk.

　　Chaucer'sstory,theNun'sPriest'sTale,writtenc.1400,takesplaceon32March;thatis,1April;itisChanticleerandtheFox,astoryoftwofools.

　　3.Well-knownhoaxes

　　AlabamaChangestheValueofPi:TheApril1998newsletterofNewMexicansforScienceandReasoncontainedanarticleclaimingthattheAlabamaLegislaturehadvotedtochangethevalueofthemathematicalconstantpit