From as early as the nineteenth century, Friday was seen as an unlucky day and thirteen was viewed as an unlucky number. This is one theory of why Friday the 13th is viewed as an unlucky day. There is another theory based on a Norse myth. The myth says that Frigga — Friday — was the goddess of love and fertility. The myth also says that when Norse and German tribes converted to Christianity, they banished Frigga and labeled her as a witch. As a result, she convened with eleven other witches and a devil, bringing their number to thirteen. This group convened to bring ill fate to the rest of the world.