Can you tell me why the ring...

We can tell you why, but the theory no longer holds water. For centuries, it was believed that the ring finger had a nerve running through it that was connected to the heart. The Romans and Greeks used the medical finger for stirring mixtures, especially in alchemy, with the belief that anything noxious would be immediately detected by way of some warning sign at the heart. This direct connection — which years later was proved to be false — was why it was chosen as the ring finger, marking the heart’s sentiment. English superstition still holds that the ring finger should be used for applying ointments or salves or for scratching the skin.