Reggie Foster is not what most people have in mind when they imagine the Vatican's chief Latin expert.

Foster, 65, a Carmelite monk, plays the role of the brash curmudgeon, especially for the 150 new students he commands each year at Rome's Gregorian University. He growls at them in perfect Latin that he mixes with mild profanities in both English and Italian.

A demanding teacher and translator, he doesn't fit the typical image of an academic steeped in a dead language. A plumber's son raised in Milwaukee, Foster governs his realm from a throne-like chair, its faux-leather cushion worn down to a thin veneer. He sits in it wearing his favored attire: a faded blue janitor-style outfit. His glasses are held to his bald head by a green rubber band wrapped around one ear piece. Between lecture points, he has been known to swig wine directly from the bottle.

But as unlikely as it sounds, Foster is the Vatican's leading expert on Latin - expert enough to be charged with the official translation of papal documents into what was until 40 years ago the official language of the church.

With new Pope Benedict XVI a strong proponent of Latin - as a cardinal he said the language should not have been completely eliminated from the Catholic Mass - Foster now may have a well-connected fellow Latin evangelist ensconced at the Holy See.

From his office inside the Vatican, Foster and the rest of the five-person team of what he calls "linguistic technicians" correct the Latin versions of various papal encyclicals and other church documents. During the period between Pope John Paul II's funeral and the selection of Benedict, Foster and the others were perfecting the Latin liturgy to be read at Sunday's installation Mass.

In addition to his Vatican duties and the courses he teaches at Gregorian University, Foster uses every opportunity to promote Latin and keep it alive.

"Without Latin you are missing out on the whole of Western culture! Without Latin you should just stay in bed!" he exclaims. "The schools don't teach it! The church doesn't use it anymore! Latin is being lost, and because of that we are losing our history!"

Foster began studying Latin at age 13 at St. Francis Minor Seminary in Milwaukee, according to the Catholic Herald, a newspaper published by Milwaukee's archbishop. He returns annually to visit his sister and the nuns who taught him, the paper reported.

Until the end of the Second Vatican Council in 1965, the Roman Catholic Mass was celebrated in Latin. Before that, generations of churchgoers could recite their prayers in Latin. Since then, Foster reports, the number of Latin students in schools has dropped.

But Foster says the language is no less relevant now. He rattles off the names of some of the great thinkers who wrote in Latin: Cicero, Galileo, Augustine, Horace, Aquinas and Ovid. Can't they be read in translation? Foster waves his hand. "That's like giving a translation of Shakespeare to a Chinese man," he says. "No doubt about it, something's going to be lost."

Although Foster has an American passport, he has lived in Rome for 42 of his 65 years. In addition to English, he is fluent in Italian. But he says he prefers Latin, the language he uses to write notes to himself and that even dominates his dreams.

He estimates there are only about 20 people in the world who speak Latin as well as he does, and only two or three of them are younger than 60.

The future of the language, he admits, does not look bright. That is one reason for his evangelism for the language. People who know Foster say the colorful, offbeat persona he has adopted makes him more approachable than he might be if he were viewed as a stuffy and famous academic.

"He makes these hilarious and irreverent comments, but there is always a premeditated point to them," says Ricardo Harris-Fuentes, 28, an artist who is taking Foster's class. "Everyone notices that Reggie is continually looking at his little pocket watch. That's because his whole day is planned out. He doesn't have time to spare."

The Rev. Gary Coulter, 32, a pastor in Ashland, Neb., and an alumnus of two of Foster's classes, says that Foster is without peer as a Latinist. "Reggie may be a little rough around the edges," Coulter says. "But there is no better teacher of Latin in the world."

Foster demurs. "I'm trying to help people who want to learn Latin," he says with a shrug. "But there is only so much one man can do."

Unless that man is the pope. Foster notes that the newly installed Pope Benedict XVI, the former Cardinal Joseph Ratzinger of Germany, speaks excellent Latin. "The problem comes with those under him, the bishops, the priests, the seminarians," Foster says. "They don't have a clue!"

Though he recognizes it is unlikely, Foster says the language would get a great boost if Benedict XVI used Latin more than previous popes. "Latin is a beautiful and poetic language, and people would pay attention to it if the pope spoke the language, spoke it from his heart," Foster says.

He says he would be thrilled to see the pontiff go to New York and address the United Nations in Latin. "The pope could stand there before the nations of the world and say, 'Vobiscum loquar lingua Latina! Haec mihi videntur facienda esse!' ('I am speaking with you in the Latin language! It seems to me that these things need to be done!')," Foster suggests.

His eyes sparkle, and he flashes a mischievous grin: "He could speak to them in Latin and tell them that if they don't like it, they can just go home!"