Papal reforms at the turn of the last Millennium attempted to impose monastic-style celibacy on the so-called "secular clergy", such as parish priests and bishops. The move was met with resistance, varying in strength between regions and countries. For example, clergy in Normandy and Spain defended their rights to a family life, but celibacy found readier acceptance in England.
The different responses to clerical celibacy and the ways in which it affected concepts of masculinity are among the principal themes of the book Religious Men and Masculine Identity in the Middle Ages, edited by the University of Huddersfield's historians Dr Pat Cullum and Dr Katherine Lewis.
Dr Cullum explained that clerical celibacy was a development that took place gradually between the 10th and 12th centuries.
"Before then, although monks were expected to be celibate, secular clergy were not. But for a number of reasons the Church decided that all clergy should adhere to the monastic model. Several of the chapters in the new book address this period, because there was quite a lot of resistance."
The usual assumption, said Dr Cullum, is that clergy resisted celibacy because they did not want to give up on their sex lives.
"But the chapters in our book show that there was a real intellectual rationale for secular clergy being able to marry if they chose. Living with wives and families gave them a status as married men that was recognisable to their parishioners.
"There was no attack on celibacy as an idea - indeed many clergy said that it was a really good thing, but it was very, very hard! If you chose to be a monk then being celibate was part of the package, but it was argued that there should also be a place in the world for men who were religious and wanted to be clergymen but didn't have the gift of celibacy."
It was also feared, said Dr Cullum, that if clergy were forced to be celibate, the chances were that some of them may not be able to manage it.
"You would be putting people in a situation where they were likely to sin and this was a bad thing to do."
The Bishop's Eye
Religious Men and Masculine Identity in the Middle Ages has an introduction by the two editors and 11 chapters by scholars based at universities in the UK and overseas. The book covers a broad period - from late antiquity to the 15th century - and includes a wide range of subjects and themes. There are chapters that deal with a crusading Bishop, the legendary figure of Hereward the Wake, the medieval prior John of Bridlington and why medieval men chose to become monks.
Dr Lewis examines the reputation of King Henry VI, who was deposed and murdered in 1471 and later venerated for his piety - an image of holiness that he might have carefully constructed himself. Dr Cullum explores men's devotion to the Eucharist and differences between masculine and female religious practice.
The book and its content are the result of a conference entitled Religious Men in the Middle Ages that took place at the University of Huddersfield in July, 2012. There is already a large amount of scholarship dealing with female piety in the medieval period. Now the aim is to build up a body of work that investigates aspects of men and religion, said Dr Cullum. A special research network has been formed in tandem with Lincoln University. It is named The Bishop's Eye - from a famous stained-glass window in Lincoln Cathedral - and a second conference is planned for next year.
Meanwhile, as historians reach a greater understanding of the origins of priestly celibacy, the Vatican's new secretary of state, Archbishop Pietro Parolin, has said that the policy is open to discussion - after a thousand years.
"It does feel a bit like the wheel of history turning!" said Dr Cullum. "But in the period around 1100 there was a very high value placed on celibacy, even though it was thought to be so difficult that only a few men could aspire to it.
"On the other hand, we live in a period when almost nobody thinks that celibacy is a good idea and it is generally regarded as a bit odd. So there are major differences between the circumstances now and in the pre-Gregorian reform period."
- Religious Men and Masculine Identity in the Middle Ages is published by Boydell and Brewer