Why the left hand?

Is a palm-reader
the same as
a Palm Pilot?

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 cultures¹ the ring is worn on the right hand, 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.

Japanese call the ring-finger kusuri-yubi, in German Arzt-Finger, in Latin digitus medicinalis and in Old Anglo-Saxon it was called lech-man, all meaning medical finger, because:

1. Patient: "It hurts when I press here, here, and here."
   
   Doctor: "You've broken your finger"

   Long ago doctors applied medical ointment with this finger.

   Sure, any finger could have been used but this finger seems 'natural' because the hand can be steadied by the middle finger and the little finger whilst applying the medicine. Being closer to the thumb, the first and second fingers are generally used more for other things (such as fingers crossed that the marriage is a happy one!), so the third finger is slightly more sensitive to touch, making it more suitable for delicate tasks like applying ointment.

   or...

2. Did Roman paramedics refer to IV's as 4's?

   Long ago people believed that a nerve or vein ran directly from this finger to the heart.

   Roman doctors called this vena amoris - the vein of love. If medicine was applied by this finger, then the medicine would be enhanced by the mystical energy of the physician's heart. Medicine has its roots in magic (medico - to heal by magic) and the German Arzt (physician) originally meant magician.

   or...

3. If medicine is applied to this finger, then the medicine would shoot directly to the heart. Nice idea.

   or...

4. ...something else.

Whatever the original reasoning was, this finger became rather special and the natural choice to bear a wedding ring.

Interestingly (well, OK, maybe not so interesting), recent studies² suggest that the length of the ring-finger, relative to the length of other fingers, is determined by the prenatal exposure to higher levels of testosterone. And higher levels of testosterone can affect one's ability in sport, language acquisition, susceptibility to autism, analytical superiority, sexual orientation, visual-motor skills, etc. A much greater brain-shaping influence is likely to be one's experiences, opportunities and environment, but the ring-finger length ratio remains an appealing study for psychologists.

Some cultures have different traditions. The Irish, for example, have an interesting 'code', where the position of a ring can send a subtle message to prospective suitors. (See Claddagh Ring.)

As most people are right-handed, the right hand is used more frequently for work, so not as touch sensitive as the left. And because the right hand does more work, it poses a greater risk of damage to any jewelry. Watchmakers put the winder on the right hand side of the watch face, because most people wear their watches on the 'safer' left wrist. A groom stands to the right of his bride so his stronger right arm is free to ward off potential kidnappers. (Jewish weddings see the groom standing to the left, based on Psalm 45:9)