Why do we use the third finger of the left hand?



But even in these days of cardiothoracic science, it's not easy to put a ring around the heart. So in the old days they had a simple answer: they put the ring on the third finger which they believed had a vein, artery or nerve (a sort of a USB cable) running directly to the heart. And as the left hand is a bit closer to the heart than the right, they placed engagement and wedding rings on the third finger of the left hand. (In some period of the past, the ring was worn on the right hand; a practice that continues to this day in some cultures, since the right hand is considered more righteous.)

In chiromancy (a combination of astrology and palmistry) the third (Apollo) finger relates to the heart. Wearing a ring on that finger would not only protect the heart from evil spirits, but also enhance the life of the wearer by transmitting energy to the heart.

Following this line of quacky reasoning, it was the custom for physicians, herbalists and other healers, to use their third finger when applying medicinal ointment or powder to their patients, Using this finger strengthened the effectiveness of the cure.