There is a story about the invention of the tea bag. In 1900s, a New York tea merchant named Thomas Sullivan often sent samples of tea to potential customers. In order to reduce the cost, he thought of a way, that is to pack a little loose tea leaves in several small silk bags. At that time, some customers who had never made tea before received those silk bags, due to they were not very clear about the procedure of making tea, so they often threw these silk bags into the boiling water. But gradually, people found that the tea packaged in this way is convenient and easy to use, and gradually formed the habit of packaging tea in small bags. Later, someone suggested to him that the silk bag was too fine, so he switched to cotton gauze and officially sold it commercially.