I''ve been trying for years to find out what the traditional birthday greeting: "Many Happy Returns"

I've been trying for years to find out what the traditional birthday greeting: "Many Happy Returns" means exactly. Anybody know?

Chris Prophet, Sweden

• It is short for "many happy returns of the day" and means that the person, who is speaking, is wishing that the person with the birthday will have many more of them, i.e. that their birthday will return many times more and that they will therefore live a long life.

  Liz, Nyköping Sweden

• Many returns of your birthday. A wish for a long life.

  Jonathan, Lancaster, UK

• I've heard an astronomical explanation of this - the sun returns to the same place in the ecliptic (a solar return), hence the wish that this will happen many more times.

  Simon, Malmo, Sweden