In classical times, lemon balm was used by both the Greeks and Romans to relieve anxiety and treat snakebites. The Arabs also used it to strengthen the heart. Shakespeare knew that lemon balm had healing properties. In The Merry Wives of Windsor he called it a sprinkling herb, something you throw on the ground before a party so that the scent makes the guests happier.
The Doctrine of Signatures, a medieval way of treating diseases with herbs, states that the appearance of a plant reveals its healing properties. Lemon balm, with its heart-shaped leaves, is said to promote heart health. Amazingly, current research proves this to be true!