Why do we wear our engagement rings and wedding rings on the fourth finger of the left hand and not on some other finger?

Why do we wear our engagement rings and wedding rings on the fourth finger of the left hand and not on some other finger?

It is a tradition that goes way back to the ancient Greeks and Romans who believed there was a special nerve that ran from that finger to the heart. Why they thought this, I don't know. I guess it just seemed like a good idea at the time.Later on, in the Middle Ages, it evolved into the idea that there was special blood vessel between the ring finger and heart. This was called the vena amoris or "love vein."