But what were those words, around the year 1600? Dr Perse could never have heard Galatians. I am making a linguistic, not a theological point. What he would have heard was (in a rough transcription) 'Galairseeans'. And in Ezekiel he would have heard 'rebellious nair-see-an' and 'lamentair-seeans and mournin', with the [r] firmly pronounced. How do we know all this? How do we know, for example, that the r was pronounced in mourning? Because writers at the time tell us that it was. Ben Jonson (the dramatist, but also the author of an English Grammar written some time in the early 1600s) tells us that r 'is the dog's letter' (littera canina) - think grrr - which is 'sounded' at the ends of words. And this kind of evidence, along with the study of spellings, and of rhymes and puns that no longer work in modern English, enable us to reconstruct how words would have been pronounced in earlier times - original pronunciation (or OP), as it is often called these days. This is part of the subject of linguistics, which I profess.

Dr Perse's surname needs to be thought of in the same way. Of course, one can never be totally certain about names, as people can pronounce their names in any way they like, as famous examples like [fanshaw], spelled  Featherstonehaugh, illustrate. But assuming that his surname followed the general sound pattern of the time, it would have been [parse], not [purse] - once again, the [r] would have been sounded, and spellings show that vowels which today are pronounced [er] were then pronounced [ar] - as we still hear in many modern dialects (mercy pronounced marcy, for instance). So I am giving 'Doctor Parse's sarmon' today.

The overall effect is strikingly different, and you will certainly have encountered it sporadically in singing. 'And grant us thy salvation' - 'sal-va-see-on'. But you probably won't have heard whole passages read in OP. Speak with my words unto them? This is how Paul would have sounded then (in the transcription that follows, the distinctive pronunciations are shown using symbols from the International Phonetic Alphabet):

But I certify you, brethren, that the gospel which was preached of me is not after man. For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ. For ye have heard of my conversation in time past in the Jews' religion, how that beyond measure I persecuted the church of God, and wasted it: And profited in the Jews' religion above many my equals in mine own nation, being more exceedingly zealous of the traditions of my fathers.

But əɪ cɐɹtifəɪ you, brethren, that the gospel ʍich was preached of me is not a:təɹ man. Foɹ əɪ nɛthəɹ received it of man, nɛthəɹ was əɪ taught it, but bəɪ the revelɛ:sɪən of Jesus Chrəɪst. Foɹ ye have hɐɹd of məɪ  convəɹsɛ:sɪən in təɪme pæst in the Jews' religɪən, həʊ that beyond measəɹ əɪ pɐɹsecuted the chɐɹch of God, and wæsted it: And profited in the Jews' religɪən abɣve mæny məɪ equals in mɪn o:wn nɛ:sɪən, being moɹe exceedingləɪ zealous of the tradisɪəns of mɪ fæthəɹs.

The period when Dr Perse was alive has been especially well studied, as it contains two of the most important influences on the development of the English language: Shakespeare and the King James Bible. Some of you may have been at Shakespeare's Globe in 2004 and 2005 when the company mounted productions of Romeo and Juliet and Troilus and Cressida in OP. Indeed, the history of OP productions goes back much farther than that: here at Cambridge in 1952 the Shakespearean director John Barton put on a production of Julius Caesar in OP for the Marlowe Society.

But the OP movement has had a new lease of life in the last decade, with productions of several Shakespeare plays in Britain and the USA, and the language used by other personalities of the period presented in this way. You can now hear, for example, William Byrd's Great Service recorded in OP by Musica Contexta (Chandos CHAN 0789). And there is the fascinating Virtual St Paul's Cross project, a digital recreation of a day's worship at St Paul's in 1623, including an OP rendition of the famous 'gunpowder plot' sermon preached by John Donne on 5th November. The project, directed by a team from North Carolina University, asks, and answers, the question: how could a crowd of up to 3000 or so people have actually been able to hear a sermon preached in St Paul's Churchyard. What would it have sounded like? You can hear the results online now (http://vpcp.chass.ncsu.edu).

'Thou shalt speak my words unto them.' Dr Perse was living at a time when there was huge debate over what those words should be. The 16th century has been called 'the age of Bibles', from the numerous translations that were made, beginning with William Tyndale's in 1625 and ending with the King James Bible of 1611. Both of these versions have been given an OP treatment: a complete St Matthew Gospel is now available on a British Library CD - really interesting because all those silent letters in English were being sounded then, to great effect (in Matthew 8.12, for instance, there was 'weeping and gnashing of teeth'). And during the 400th anniversary of the KJB, there were several readings of extracts in OP.

I remember that year well, as it brought me a different historical linguistic encounter. I was asked to write a book on the influence of the KJB on the English language, and I was very happy to do so for two reasons. I was disturbed by the exaggerated claims that were being made about the linguistic impact of this work. At the same time, I had no evidence to rebut these claims. I felt I needed to explode the myths and replace them by some facts.

First, the claims. 'No book has had greater influence on the English language', said Alan G Thomas in his Great Books and Book Collectors. Winston Churchill called it a 'masterpiece', uniting English-speaking peoples everywhere. Samuel Taylor Coleridge claimed its study would 'keep any writer from being vulgar, in point of style'. And here's another quote: the KJB was 'an enormous force in shaping the development of the English language'. That's not from a historical linguist. This was film-star Charlton Heston. He read the KJB while preparing to play Moses in The Ten Commandments.

I can live with the spirit of these claims, but I become uneasy when I read people like MP Frank Field happily quoting Melvyn Bragg (in The Tablet, 3 April 2010) that the KJB is 'the DNA of the English language'. It's a striking metaphor, but a hugely misleading one. DNA is in every cell we possess; but the style of the King James Bible is by no means in every word we write. On the contrary, there are many features of its language and style that are no longer part of English. We notice the changes straight away as we read: old spellings such as pluckt; old punctuation such as our's; old vocabulary such as peradventure; old grammar such as verb endings (moveth), past tenses (builded), and word orders (in the likeness of God made he him). When we read such a sentence as in the day that thou eatest thereof thou shalt surely die, there's only a limited sense of continuity with today's English. Or take this: And every man that offered offered an offering of gold unto the Lord. No modern copyeditor would let such repetitions survive. Our stylistic fashions have changed.

So wherein lies the influence of the KJB on present-day English? What people are usually thinking of are the many idioms that have come into the language with a biblical origin - such as out of the mouths of babes, fly in the  ointment, and thorn in the flesh. But ask yourself the question: 'How many such items are there?' The mind goes blank! You might think fifty, or a hundred, or a thousand or more.

I had no idea either, so when the 400th anniversary loomed, I used it as the motivation to do a proper count. I read the whole KJB through, looking out for any phrase that I felt had come to be a part of modern English, whether people were aware of the biblical connection or not. In fact, I read it through twice, in a week, to check that I hadn't missed any on my first reading. Such a task is not for the faint-hearetd, and is probably eligible for the Guiness Book of Records.

I made two discoveries, reported in the book that eventually appeared: Begat (OUP, 2010). First, there are not as many idioms as some people think: I found only 257. And second, most of the idioms don't originate in the King James translation at all. Rather they are to be found in one of the translations that appeared in the preceding 130 years - such as Wycliffe, Tyndale, the Bishops' Bible, the Geneva Bible, and even (despite its Catholic origins) Douai-Rheims. By my count, only 18 expressions are stylistically unique to the King James version, such as a thorn in the flesh, how are the mighty fallen, and the hugely apposite (to this congregation) much study is a weariness of the flesh. Every other idiomatic expression is shared with at least one earlier translation. In many cases, an idiom is found in all of them - such as milk and honey or salt of the earth. We don't have to read far before we encounter one: there were none in the readings we have just heard, but a little later in Ezekiel we find The fathers have eaten sour grapes (18.2) and Thou shalt be fuel to the fire (21.32).

A figure of only 257 means that we mustn't exaggerate the influence of the KJB on English. On the other hand, it's true to say that no other literary source has matched this version for the number of influential expressions it contains. Not even Shakespeare introduced so many idioms into English. And it's true to say that no other source reached so many people. Even though the KJB didn't originate, it certainly popularized. It gave the idioms a widespread public presence through the work being 'appointed to be read in Churches'. No other translation reached so many people over so long a period. It was auditory consciousness that did it. Literacy levels were still very low in the 17th century, and for most people their encounter with the Bible would have been 'through the air' - via church homilies or the powerful words of itinerant preachers. Reading aloud was facilitated by the punctuation, which was more an aid to speech than a guide to grammar. And the rhythm of the language had a direct influence on the way its phrases entered modern idiom.

To see this, we have to understand first that one of the important functions of rhythm is to aid auditory memory. Virtually all the idioms that show the influence of the Bible are short: the average length of the 257 expressions I found is 4.3 words. And when we examine individual instances, we can see the way in which usage has favoured that norm. Take fly in the ointment. This does not in fact turn up in any biblical translation. King James has Dead flies cause the ointment of the apothecary to send forth a stinking savour. How do we get from there to fly in the ointment?

Comparing other translations is the key: Wycliffe (flies that die, lessen the sweetness of ointment), Geneva (dead flies cause to stink, and putrefy the ointment), and Bishop's (a dead fly doth corrupt sweet ointment). What's the difference? The other translations separate the critical words, flies and ointment. King James brings them together: flies cause the ointment. This puts them into the same chunk of working auditory memory: they are more likely to be retained by the listener. And it is then a relatively short step to adapt the phrasing to one of the commonest rhythmical patterns in English:

flies cause the ointment > flies in the ointment > fly in the ointment

Compare: bee in the bonnet, head in the sand, stain on the character, and hundreds more. It doesn't happen straight away. It took nearly a century before we find the first recorded instance of fly in the ointment.

The result of this largely auditory process was that an unprecedented number of biblical idioms captured the public imagination, so much so that it's now impossible to find an area of contemporary expression that doesn't use them, either literally or playfully. We find them in such disparate worlds as nuclear physics, court cases, TV sitcoms, recipe books, punk rock lyrics, and video games, adapted in all kinds of imaginative ways. When I was researching my book, I read of a political confrontation headlined Bush is the fly in Blair's ointment. A blog about the search for Osama Bin Laden, at the time his whereabouts still unknown, was headed Seek and ye shall seek. No other work has generated so many variations. The adaptations are legion. Seek sources on the Internet, and you will easily find them. In this sense, the influence of the King James Bible is without parallel.

To take just one example in a bit more detail, from Genesis: Am I my brother's keeper? The idiom turns up as a headline for reports on events in prisons, borstals, hospitals, mental health institutions, nursing homes, philanthropic foundations, and other places which guard people or care for them. It has been a title for over a dozen episodes in television series, such as Knight Rider, Law and Order, ER, Tales from the Crypt, and the first episode of Miami Vice. It has been the title of books and record albums. With a gender change, it has named a Walt Disney cartoon (Her brother's keeper), and there are several books and films called My sister's keeper. Some people go out of their way to avoid any hint of sexism. Barack Obama's Christmas Day message in 2008 affirmed that 'we share a common destiny as Americans - that I am my brother's keeper, I am my sister's keeper.' Some reports increase the number of possessives. In 2008, a Wisconsin court ruled that a homeowner looking after someone else's dog was liable for any personal injury caused if the dog ran out of the house and attacked a passer-by: the headline was Am I my brother's dog's keeper? And there even more-ingenious creations, such as the story of the ape in the zoo caught reading Darwin and asking: Am I my Keeper's brother?

All this produces a new take on the command: 'thou shalt speak my words unto them'. The words are clearly still being spoken, and have penetrated modern English linguistic consciousness in extraordinarily unpredictable and unprecedented ways. The linguistic task is done. But of course the exegetical and prophetic tasks remain. As Ezekiel goes on to say: 'thou shalt speak my words unto them, whether they will hear, or whether they will forbear: for they are most rebellious'. I like to think that, once we become more aware of how we echo biblical language in our everyday usage (whatever the pronunciation), it makes us reflect that little bit more deeply on the spiritual realities towards which the words are acting as signposts?