14th-Century. At that time, the use of the Printing Press, which allowed the printing of any number of Missals in large and small volumes, no longer permitted it to remain hidden as it had been, and, in the following Century, the heresies of Luther and Calvin, who dared to blaspheme against The Mass, obliged many of The Laity to read it and examine its Prayers, because it was so hotly disputed.
The Councils of Mainz and of Cologne, in 1547, ordered it to be explained to the people. This decision was confirmed at The Council of Trent, which enjoined Priests to explain, on Sundays and Feasts, some of the Mysteries of The Mass, and what was read in it, so that The Faithful would be, not only well instructed concerning the truth of the Mystery, but also the meaning of the Prayers and Ceremonies.
The Council desired, further, that Priests explain the Sacramental formulas, and that Bishops have them Translated into the Vulgar Languages to facilitate their understanding by the people.
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