When Matthew Morrison starting playing Lieutenant Joseph Cable last March, he was grateful to have such a plum role in a great musical receiving its first Broadway revival. Initially, however, there was a problem. "I found that most nights I would leave the theater in a bad mood," Morrison said the other evening in his dressing room, whose walls reflect his fascination with James Dean.

"Just as the defining challenge for my role in Hairspray was physical," Morrison said, "and the defining challenge for me in The Light in the Piazzawas vocal, the trick to playing Cable involves the feelings you need to convey." Playing him requires that you go on this difficult emotional journey every night, continued Morrison, who will be ending his South Pacific assignment on January 4th. "He's conflicted about his love for Liat. He's being sent on a mission from which he probably won't return. Plus he has malaria. I had to learn to pace myself in order to keep going with the run. Once I did, things got a lot easier."

For Morrison, who grew up in northern California before moving south to attend the Orange County High School of the Arts, the residue of South Pacific involves more than Cable's emotional life. "I talked to a lot of World War II veterans as a result of playing this role. They helped me to understand how Cable could have fallen in love so quickly with Liat. Those soldiers hungered for the company of the opposite sex. The touch of a woman meant so much."

Some veterans, however, had other thoughts once they returned home. "They said they would look at the photos of some of these women years later," Morrison said, "and they would find they were not as beautiful as they remembered." So does Morrison think that, if Cable's fate had been different, his response would have been similar to those of the veterans?

"Probably so," the actor responded. "In the moment, Cable says he wants to stay with Liat. But if his fate had been different, he probably would have fallen back in line, and returned to Philadelphia."

Speaking of returns, Morrison's life post-Pacific will take him back to his native California. There's sadness about ending his second run at Lincoln Center Theater (Piazza was the first), but he's also a little relieved to be leaving the New York cold and excited about his next assignment: a television show called "Glee."

"Glee" is the brainchild of Ryan Murphy, who also created "Nip/Tuck." Set to premiere on Fox in late March/early April, just after "American Idol," "Glee" takes place in an Ohio high school. Morrison plays the lead character, Will Shuester, a Spanish teacher who directs the school's glee club. The singing group has fallen on hard times. "It only has five kids," Morrison said, "and they're all outcasts. The goal of my character is to restore the glee club's status. The show has surreal touches -- a heightened reality. And some people might say that it taps into the High School Musical vibe out there."

Morrison plans to spend the month between his departure from South Pacificand his resumption of shooting "Glee" (he took a break from SP during the fall to shoot the pilot episode) in Hawaii, with his girlfriend. She and he met this past July, and since it's a fairly new relationship I'm going to respect Morrison's desire to protect most of its details.

I can reveal, however, that Morrison was introduced to his girlfriend by Loretta Ables Sayre, South Pacific's Bloody Mary. In the show, of course, Bloody Mary introduces Cable to Liat. "It's a cliche, but a true one," said Morrison. "Sometimes, life imitates art."

BRENDAN LEMON is the American theater critic for the Financial Times and the editor of lemonwade.com