Red heart pierced by the Cupid's arrow is a traditional symbol of Valentine's Day. Heart symbolizes love and giving someone a heart means to hand over one's existence to someone. A heart pierced by a Cupid's arrow means that when someone presents a heart, the person takes the risk of being rejected and feeling hurt. Piercing arrow therefore symbolizes death and vulnerability of love. Some people also believe that the heart and arrow symbolizes the uniting of male and a female.
Today, one finds great use of red heart symbol especially heart shaped red balloons in Valentine's Day decoration. Stuffed red heart decorated with a lace is a popular Valentine's Day Gift.
Around 12th Century people were not aware the function of heart was to circulate blood inside the human body. What they knew was that heart begins to beat faster when a person is upset or excited. They, therefore, derived that heart was the seat of emotions and feelings. Poets too eulogized the role of heart in feelings of love and romance and over the years this make believe connection between heart and love became deep seated in the minds of people. Today, even though it has been scientifically proved that emotions come from the brain heart remains a powerful symbol of love and Valentine's Day.
The popular expression of 'Wearing one's heart on one's sleeve' comes from the tradition prevalent in America and Britain around 1800s. At that time, young men used to wear slips of paper pinned on their sleeves and had their girlfriend's name written on it.