Heretics are traditionally thought of as renegades or deviants. But according to Louisa Burnham, they should be viewed as reformers.

Burnham, an NU medieval history lecturer, said Tuesday that figures such as Thomas Aquinas and Joan of Arc walk a fine line between heretics and saints in a speech titled “Saints and Sinners in the Late Medieval Ages.”

Burnham said it is easy to think a person was a heretic during the medieval ages because they disagreed with the church. But according to Burnham, heretics actually tried to improve the church.

“Reformers of every kind are people who help to define the church,” Burnham said.

The lecture, held at the Evanston Public Library, was part of a monthly community reading group called the Time Travelers. The group began last year, beginning with prehistory and proceeding chronologically through several ancient civilizations.

Among the approximately 70 residents at the lecture was Bill Neilson, Weinberg ’78, who said he has regularly attended the lectures.

“This event really helped organize a couple of themes of heresy and mainstreaming in the church in the Middle Ages,” he said. “I try to attend every one of the lectures because no matter how much you think you’ve read on a subject or experienced yourself, there’s always more information to be learned.”

Burnham spoke chronologically about the heretical groups, one of which was the Cathars. Unlike the other groups, this one did not have a charismatic founder and appeared in Western Europe during the 11th century.

“There is a strange concentration of heretic movements that flourished and grew in the south of France,” she said.

Burnham said Cathars believed there were two beliefs to the word’s origins. One is derived from the Greek word “catharos,” meaning pure. The other thought stems from the German word “katze,” meaning cat.

“The leaders of the Cathars were very pure. They wouldn’t eat meat,” Burnham said.

The Cathars were dualists who believed that there was a good god and a bad god. According to their beliefs, the bad god created everything that was earthly and physical, Burnham said.

“The Cathars tried to get as close to the good god as possible,” she said. “Cathars did not have an alternative philosophy, they were just good Christians.”

“The Cathars were not as out in left field as some recent books make them out to be,” she said.

Burnham said her passion for the Middle Ages started at a young age.

“I’ve been a Medievalist since the cradle,” she said. After writing her first paper about the medieval ages called “What medieval people ate” in second grade, she read the book “Montaillou” on the beach when she was 17.

Burnham received her undergraduate degree in 1987 in medieval history from Harvard University. She then taught French, Latin and history in high schools in New York, Connecticut and Boston. She received her doctorate in medieval history in 2000 from Northwestern.

Currently an adjunct lecturer at NU this quarter, she is teaching a history class titled Saints or Sinners in Medieval and Early Modern Europe.