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The origins of this gesture are highly speculative, but is quite possibly 2500 years old. It is identified as the digitus impudicus ('impudent finger') in Ancient Roman writings and reference is made to using the finger in the Ancient Greek comedy The Clouds by Aristophanes. It was defined there as a gesture intended to insult another. It has been noted that the gesture resembles an erect penis.
Ancient Romans also considered an image of an erect phallus as a talisman against evil spells. As a consequence, displaying this gesture to another may not have been a pseudo-sexual insult but rather an insulting statement along the lines of—"I'm going to protect myself against your witchcraft, before you even start" but an even earlier reference is made to ancient farmers using this finger to test hens for coming eggs.
A story that refers to the gestures of longbowmen fighting in the English army at the Battle of Agincourt in particular is often mentioned. The French cut off fingers from captured archers (usually the index and middle finger of the right hand). The English longbowmen who retained their index and middle fingers held them up in a V gesture (V Sign) to show they could still operate their weapons, and this gesture is still offensive in Britain today. Whether this has anything to do with the middle finger salute is unknown, but unlikely. According to internet legend, Tom and Ray Magliozzi, a.k.a. Click and Clack, the Tappet Brothers from Car Talk, read a version of this story for one of their "puzzlers". This story has circulated as an e-mail since 1996. Although many people read the e-mail as a serious account, it is more likely meant to be read "tongue in cheek". Whether or not the story originated on Car Talk is unknown.
Jean Froissart (circa 1337-circa 1404) was a historian as the author of the Chronicle, a document that is essential to an understanding of Europe in the fourteenth century and to the twists and turns taken by the Hundred Years' War. The Chronicle is a primary source of information. The story of the English waving their fingers at the French is told in the first person account by Jean Froissart. However, the description is not of an incident at the Battle of Agincourt, but rather at the siege of a castle nearby in the Hundred Years War. Adding to the evidence is that by all accounts Jean Froissart died before the Battle of Agincourt, thus making it rather difficult for him to have written about it. (SOURCE)
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