How has the Liturgy of the Roman rite developed and changed in history before and after the Council of Trent? What principles have determined the boundaries of legitimate liturgical reform over the centuries? What was the Liturgical Movement? Did GuTranger, Beauduin, Guardini, Parsch, Casel, Bugnini, Jungmann, Bouyer and the Movement's other leaders know and respect these principles? And what is to be said of the not insignificant liturgical reforms...