NEW YORK (CNN) -- They've been teasing and tantalizing female readers with images of muscular men oozing sensuality and the pretty women they are destined to save and then fall in love with. The "beefcakes and bodices" book covers have helped Harlequin sell their romance novels for more than half a century.



Powerful men and demure women were stock in trade in early Harlequin novels.



"It's always great to feel like you're the girl in the book and the handsome guy is coming to rescue you," said Liz Lenz, 25, who has been reading Harlequin novels since she was a teen. "It's always fun for the reader."



Those covers also seduced Winnipeg, Canada, teacher Louann Bergen.



"There's usually good-looking males on the covers or something intriguing to make you want to read more," she said. "I guess they change with the times, but they still have that same allure and that same passion behind them."



As sort of a 60th anniversary gift to its faithful readers, Harlequin is displaying original artwork for its covers in an New York exhibit called "The Heart of a Woman: Harlequin Cover Art 1949-2009."



And before you sniff disdainfully at romance novel art, be reminded: That artwork sells a lot of books. Romance fiction is responsible for $1.375 billion in book sales every year, according to Romance Writers of America. The organization says more than a quarter of all books sold are romance novels, satisfying 51 million readers every year.



The Harlequin exhibit comes from boxes and boxes of old novels that employees discovered at the company's headquarters in Toronto, Canada.



"I pawed through literally thousands of paintings," curator Elizabeth Semmelhack said, adding that she saw apparent shifts in women's historical desires began to emerge.  Watch the curator discuss some favorites »



"Rather than being retardataire [outdated], many of these images are extremely cutting edge," she said. "There are images of women doctors before women were really embraced by the workplace. There are women who are adventuring around the world before independence is really part of women's culture."



Many early Harlequin covers, like that of Elizabeth Houghton's "Island Hospital," in which a man, woman and grizzly bear stand poised in confrontation, depict more than one (fully clothed) character in the crux of a suspenseful moment.



"You don't know, is the couple going to get together? Is the hero going to save the heroine? The happy ending is not on the cover," Semmelhack explained.



The illustrations have changed their tone over the years. Where cover art used to hint at psychological intrigue, it's grown to instead promise a passionate physical conclusion.



"From the earliest covers, there's sort of an implied sexual tension, but there isn't much direct imaging of passion. That doesn't happen until the late '70s and into the '80s," she said. "By the time you hit the sexual revolution and passion becomes of primary importance on these covers, then that lover's embrace in many ways signals the happy ending right there on the front of the book."



And in recent decades, the once revolutionary depictions of the lovers' raw embrace have been reduced further.



"Today, covers might just be the undressed male body. He might even be headless. He's so truncated that all you're doing is looking at the object of desire, his masculinity."



Although Harlequin romances are predominantly written for and read by women, according to Semmelhack, the majority of the publisher's cover illustration artists have been male.



"It is interesting that you have men imaging female desire," she said. "It seems to work; the books certainly sell."



This year, Harlequin books, which publishes 1,200 new titles annually, reported first quarter earnings up more than 13 percent.



Debbie Macomber, who has published 153 books since 1983 -- and is most recently author of a May New York Times Harlequin best-seller, "Summer
What do readers say? Where does the exhibition took place? who displays half a century of romance book covers in New York? what reader says about books? Where is the event? Who said  books still have that same allure and that same passion? who go from psychological intrigue to passionate physical conclusion?
"It's always great to feel like you're the girl in the book and the handsome guy is coming to rescue you," New York Harlequin "It's always fun for the reader." New York Louann Bergen. cover art
question: What do readers say?, answer: "It's always great to feel like you're the girl in the book and the handsome guy is coming to rescue you," | question: Where does the exhibition took place?, answer: New York | question: who displays half a century of romance book covers in New York?, answer: Harlequin | question: what reader says about books?, answer: "It's always fun for the reader." | question: Where is the event?, answer: New York | question: Who said  books still have that same allure and that same passion?, answer: Louann Bergen. | question: who go from psychological intrigue to passionate physical conclusion?, answer: cover art