The first known depiction of a heart as a symbol of romantic love, according to Wikipedia, dates to the 1250s, and occurs in a miniature decorating a capital S in a manuscript of the French Roman de la poire.
In the miniature, a kneeling lover (or more precisely, an allegory of the lover's "sweet gaze" or douz regart) offers his heart to a damsel.
You can use these envelopes to tuck a little love note into a lunch bag or coat pocket to add a smile to someone's day.
They can also be used at Valentine's Day for "secret admirer messages, party invitations or other greetings.

• Envelope size: 7*4.25in, 10 pcs per pack
• Lovers message envelope for his/her surprise
• Made of good quality kraftpaper, bright colors
• Romantic message bag with heart-shaped seal
• A special envelope to make someone's day delightful

Envelope size: 7*4.25in, 10 pcs per packBeeChamp