The O Antiphon for December 19 is O Root of Jesse (O Radix Jesse). Though not mentioned much in Old Testament, Jesse was the father of King David, from whose line the Messiah was promised to come. The line of David was almost lost when Israel went into exile and the Jerusalem temple was destroyed. But Isaiah prophesied (Is 11:1-5) that a new ruler would emerge like a root hidden beneath the soil from the line of David, a ruler who would embody the ideals of the Davidic kingship.
Learn more about the O Antiphons: http://www.simplycatholic.com/what-are-the-o-antiphons/
