"Bless You"

Why?Are these words spoken? Some people believe that your soul may escape through your nose while sneezing and people say bless you to prevent the devil from taking it.People also believe that when you sneeze your heart stops and you may die so they bless you just in case.

When?Did this saying originate? This saying dates as way back to AD77 and way farther than that.

How?How did this saying originate? This saying originated for superstitious reasons.

Where?Where did this saying originate? Some say it started in Rome to halt the plague.