Question: How do we get "our trespasses" and "those who trespass against us" from "débita nostra" and "debitóribus nostris" (in the Our Father)? What, exactly does "world without end" (in the Glory be....) mean? And, how did "Spíritus Sanctus" become the "Holy Ghost"?
Answer: To answer the questions, one must understand that in late-medieval England (say, the 1400s) the formal prayers of the Church were generally recited in Latin -- the Our Father, the Hail Mary, the Creed and so forth. A number of pastoral manuals existed to enable priests to explain these prayers to the faithful (as well as to preach and hear Confessions).1 Such summaries, of course, contained the translated words of the prayers, but usually phrase by phrase, rather than as one continuous whole. In any event, the translations were the personal work of the writers, so there were no uniform English language prayer texts in use throughout the realm. If this lack of uniformity is surprising, it ought to be remembered that prior to the Council of Trent and Pope Saint Pius V's codification of the Roman Missal even the Latin texts of the Mass varied from place to place and among religious orders.
The movement among English Catholics toward private prayer in the vernacular came roughly a century before Protestantism. John Mirk, author of well received pastoral manuals, urged priests to encourage private prayer in English:
Yet, the production of uniform texts in the vernacular suffered greatly for fear by translators that they would be associated with the Lollard heresy -- a sort of pre-Protestantism preached by John Wycliffe, which insisted on the use of an English language Bible, to be interpreted each man for himself. (Wycliffe also denied the apostolic succession, transubstantiation, and the Sacraments -- his followers were sometimes even more radical.)
The standard texts, used more or less unchanged even today by English speaking Catholics and Anglicans were issued by Henry VIII in 1541, eight years after Henry's schism from the Catholic Church. They show the influence of the unauthorized translation of William Tyndale, which was issued around the time of the schism:
Both the Catholic Douai Rheims translation of 1581 and the Protestant King James version of 1611 are more faithful to the Latin:
Nonetheless, King Henry's text has endured with only a word or two changed -- from "Our Father which art in heaven," and from "thy will be done in earth...." Certainly, the idea of "forgiving trespassers" adequately reflects what our Lord had in mind.
The ending of the Glory be... as "world without end," seems to this writer to be a case of poor translation from the Latin -- a confusion of the word "sǽcula (ages)" with "secular" or "worldly" -- a confusion aided, perhaps, by our contrast of things "temporal or worldly" with things "eternal or heavenly" -- but so commonly used that it is just accepted as an idiomatic usage. Roget's Thesaurus (1995) has an entry for it:
World without end:
Quality or state of having no end: ceaselessness, endlessness, eternality, eternalness, eternity, everlastingness, perpetuity.
Enduring for all time: amaranthine, ceaseless, endless, eternal, everlasting, immortal, never-ending, perpetual, unending. Archaic : eterne.4
Both the Douai-Rheims and King James versions use the phrase "world without end" to translate, for example, the end of the third chapter of Saint Paul's Epistle to the Ephesians. But the Vulgate Latin is "in omnes generatiónes sǽculi sæculórum," while the Greek has "τας γενεας του αιωονος των αιωονων." The phrase in the Doxology is heard throughout the Mass as "per ómnia sǽcula sæculórum, and would be more literally translated into English as "through all ages of ages," or, perhaps as "for eons of eons" if one wanted to retain the "flavor" of the Greek.
But we surely don't need any more liturgical change in our lives, and "world without end" will probably remain with English speaking Catholics for a long time to come.
Referring to the Third Person of the Trinity as the Holy Ghost is a beneficial quirk of the English language. In Latin and its derivative languages, "spiritus" or something like it is used to denote "the spirit," "the soul," "something spiritual," "the spirit of," "pride," "courage," "inspirations," and so forth. It is also used for "the breath," for in the ancient world, "spiration" or its absence was the only reliable test for life or death; of the soul being present or departed.
English has many of its words from Latin, but it also has riches of Germanic origin. The Germanic "geist" means many of the same things as the Latin "spiritus." English uses both roots, using "ghost" to refer specifically to the person -- the soul of a deceased person, or, with a capital "G," to the Third Divine Person. When the meaning is more general -- as in "the Spirit of God moved over the waters" or in "the spirit of holiness" or even in the "spirit of the law," English uses the Latin root.
One could make the case that English speaking Catholics could give up the "geist" and make use of the Latin root exclusively, but given the long term usage such a move could only lead to confusion.