The Guardian says British academic Prof. Stephen Milner stumbled across the document in Florence while researching town criers. The 1513 proclamation led to the downfall of the author of The Prince.
"When I saw it I knew exactly what it was and it was pretty exciting," said Prof Milner.
"When you realise this document marked the fall from grace of one the world's most influential political writers, it's quite a feeling.
"The Prince is a seminal work, with a lasting influence on political thought and culture. The term 'Machiavellian' and the naming of the Devil as 'Old Nick' all derive from this single work, but the circumstances of its composition have often been overlooked."