Pigs fly over New York City
answering the question of Who is the author?
The first known example of the expression in its modern form is from The Autobiography of Jack Ketch By Charles Whitehead (1835): "Yes, pigs may fly, but they're very unlikely birds".
A sarcastic remark used to indicate that an event is very unlikely and/or to question the credulity of someone. For example, "he said that he'd tidy his room today," to which somebody might reply "and pigs might fly" or other variations such as "when pigs fly" and "oh look, I think I saw a flying pig."
According to America's Popular Proverbs and Sayings by Gregory Titelman, the expression "if a pig had wings, it could fly" traces back to Proverbs of Scotland (1862).
But other sources, most notably the usually reliable phrases.org.uk, find much earlier references - the earliest being John Withals' English-Latin dictionary, A Shorte Dictionarie for Yonge Begynners (1616): "Pigs fly in the ayre with their tayles forward." In Gnomologia (1732) Thomas Fuller moved the expression closer to its modern day form: "That is as likely as to see an Hog fly."
