In a recent article in Notitiae, the new Prefect of the Congregation for Divine Worship and the Discipline of the Sacraments, Archbishop Arthur Roche, made the following claim about the textual relationship between the ‘old’ and ‘new’ Missals: While the Missal retains the basic structure of that of Saint Pius V, together with ninety percent of the texts of that Missal, it removes a number of repetitions and accretions and simplifies the language and the gestures of the liturgy. At the same time, it uses more sacrificial vocabulary than was the case in the 1570 Missal. Opinions to the contrary are false.  I will not deal here with the question of “more sacrificial vocabulary”, as this requires further detailed examination.  It is, rather, Archbishop Roche’s claim about the number of prayers from the 1962 Missal used in the post-Vatican II Missal that struck me as odd and, frankly, scarcely believable. In fairness, the new Prefect is not the only one to make such a claim: no less a figure than Annibale Bugnini wrote that: The new Missal has eighty-one prefaces and sixteen hundred prayers, or more than twice as many as in the old Missal. Almost all the texts of the old Missal have been used, revised if need be to harmonize them with the reform and the teaching of Vatican II.  This assertion stuck out to me because I have recently finished my project to detail the sources of every postcommunion oration in the 2008 Missale Romanum,  and in the course of that work I found that only about a third of those prayers have the older Missale cited as their direct source in the various published lists. It is, however, true that some prayers where the source is given as, e.g., the Gelasianum Vetus or the Leonianum are also contained in the 1962 Missale Romanum. Some centonised prayers, i.e. those that have been composed using parts of two or more pre-existing prayers, also have the older Missal as at least one of their sources. So, to arrive at the most generous and reliable figure possible, some extra work with the source lists and the ever-helpful Corpus orationum  was necessary.New Liturgical Movement: Mythbusting: How Much of the 1962 Missal is Actually Used in the Post-Vatican II Missal?