The first Sunday after Pentecost has been instituted to honor THE MOST HOLY TRINITY. In the early Church, no special Office or day was assigned for the Holy Trinity. Pope John XXII ordered the feast for the entire Church on the first Sunday after Pentecost since it was after the first great Pentecost that the doctrine of the Trinity was proclaimed to the world. The feast was raised to the dignity of a primary of the first class, in 1911, by Pius X.