#157.
The rationale for this tradition predates the early Christians and goes back to the Norse god Baldur, second son of Odin. He was so beloved by the other gods that they sought to protect him from all the dangers of the world. His mother, the goddess Frigg, "took an oath from fire and water, iron and all metals, stones and earth, from trees, sicknesses and poisons, and from all four-footed beasts, birds and creeping things, that they would not hurt Baldur." however, Loki found out that his mother forgot to ask a particular poisonous plant(name withheld on purpose) not to harm her beloved son. In the end, a dart fashioned from the little plant was used to murder Baldur. Frigg, devastated, her tears became the berries of the plant and it was decreed that the plant would never again be used as a weapon and that she would place a kiss on anyone who passed under it. Name the tradition.