Robinson Professor of the Humanities Robert D. Levin '68 walked into Literature and Arts B-54 yesterday to teach his students about the classical sonata.

But instead of the lectern, the professor headed for the piano bench. And instead of a speech, his presentation opened with a live, impassioned performance of Beethoven's Sonata Pathetique.

Levin, who came to Harvard last year, is winning rave reviews for the new class on chamber music from the late 18th century.

The professor, an acclaimed musician who can demonstrate the works instead of just talk about them, spends all of his lectures at his black Steinway grand.

"It's more like a concert than a class," says Miriam Kim '98. "His lectures encourage you to relax and feel the music."

As of yesterday, 375 people had registered for the course, two-and-a-half times the size expected.

"Why is it that every time I come to this room, there are more students?" asked head teaching fellow Sean Gallagher yesterday in his section announcements.

Students say it is Levin's hands-on style that draws them to the class.

"Professor Levin has a very inspiring manner of speaking," says Mary P. Kwaan '96, a women's studies concentrator. "It's very clear by the way he speaks that he is a full-time performer.

"He plays while he lectures and that's unusual and creative in terms of lecturing technique."

The students' enthusiasm may be a vote for more professors who perform. Levin is the only tenured professor who teaches performance, though most music professors are also expert players.

"We are a department that focuses on the study of music and we are not a conservatory, but we did hire Robert Levin as a professor for performing studies," says Music Department Chair Kay Kaufman Shelemay. "We are thrilled by the success of his new course and feel confident Professor Levin will do much to increase students' appreciation of music in this course."

Levin is an internationally known pianist who has played with Christopher Hogwood, Boston Symphony Orchestra conductor Seiji Ozawa and other famous musicians. A composer as well, he is famous for his "completions" of fragmented Mozart works.

The department will probably gain no more faculty for the next few years, Shelemay said.

It is not just Levin's piano ability that wins the undergraduates, however.

Unlike some faculty members, the professor really cares for the students in his core class, not just the expert concentrators he teaches in more advanced courses, students said.

"It is important to teach people who are going to be professional musicians the technical aspects of music and learn how to perform pieces well, but I'm much more eager to make sure that those people have an audience," Levin says. "What's the point of having brilliant scientists or musicians if there's no environment where they can bring society good?"

When playing, Levin's body sways back and forth, but he can still somehow deliver cogent sentences. Students say his lectures are vivid and interesting.

"I liked how he described the racism or lack thereof between the white and black keys of the piano," Kwaan says.

They also appreciate that the class requires no music-reading ability.

"I agree with Professor Levin's philosophy of art," says Nicholas T. Lopez '96. "Instead of using intellectualization as an end, he uses it as a means to understand the emotional and intuitive response one has to music."

For Levin, the opportunity to bring music to the people who might not learn about it otherwise is what makes teaching a large lecture worthwhile.

"I took on a challenge when I decided to teach this course," Levin says. "Chamber music is seen as not being very accessible. People think it is only for those who really love music.

"I thought, 'Why not start in this area that is considered notoriously difficult by people and make them excited about it and make some inroads?'...The number of people in the class is a heartening sign that the gamble I have taken may pan out.