This phrase was spoken by Iago in Othello (Act 1, scene 1) written by William Shakespeare in 1604.
In complement extern, ’tis not long after
But I will wear my heart upon my sleeve.
For daws to peck at. I am not what I am.
When knights fought each other, beginning in the Early Medieval Ages, they would oftentimes dedicate their performance to a woman of the court — usually someone with whom they were in love. To let their feelings be known to all, the knights publicly displayed cloths, handkerchiefs or ribbons belonging to the woman by tying it to one of his sleeves prior to his jousting match.
English chronicler, Roger of Hoveden (fl. 1174 – 1201), described jousting tournaments as “military exercises carried out, not in the spirit of hostility (nullo interveniente odio), but solely for practice and the display of prowess (pro solo exercitio, atque ostentatione virium).” The first recorded tournament was staged in 1066 when a chronicler of Tours in the late twelfth century recorded the death of an Angevin baron named Geoffroi de Preulli in 1066.
The sport did not gain widespread popularity until the 12th century and maintained its status as a popular European sport until the early 17th century. That being said, Georg Rüxner’s book Thurnierbuch (1579) details the tournament laws of Henry the Fowler, King of Germany (919-936).
Historically Speaking 