BY almost any standard, Neil Rudenstine is the Successful Teacher. He is friendly and witty and handsome. At 33, he is assistant professor of English at Harvard, giving his own upper-level courses in Elizabethan English Literature, as well as sharing the guidance of Hum 6 with venerable Reuben Brower. He has studied at Princeton (where he graduated summa cum laude in 1956) and Oxford (where he went as a Rhodes Scholar for three years) and Harvard (where he got his Ph.D. in 1964).

But the most impressive part of Rudenstine's success is the intense devotion he inspires in his students. From the grad students he guides through the esoterica of English 235 to the freshmen who slog with him through the mysteries of Hum 6, his students are uniformly enthusiastic, and their praise becomes almost monotonous.

Rudenstine's manipulation of the Hum 6 mystique has probably won him the most fans. Perched cross-legged atop a table in a dreary, third-floor Sever room, he gently probes the intricacies of Eliot and James and Shakespeare, urging his section towards the Hum 6 View of the World. It doesn't always work: the Hum 6 magic-show of extracting meaning from symbols overwhelms some students and exasperates others. But they keep coming back. "Because we love Mr. Rudenstine," a Cliffie says.

NOW Rudenstine is leaving Harvard. In July he will begin a five-year term as Dean of Students at Princeton. In his new job, he will oversee all the extra-curricular aspects of Princeton student life, while still teaching one English course a semester.

Asked why is he leaving now, after only four years at Harvard, Rudenstine quickly scotches rumors that dissatisfaction with Harvard's English Department has driven him away. "I'm leaving prematurely, it's true," he says, "but I certainly wouldn't have left Harvard at this point in order to teach English somewhere else. This chance was something new--something interesting and entirely unexpected."

Sitting in his Adams House office. Rudenstine twists his legs into a new contortion as he describes the situation that has attracted him to Princeton: "It is not so much what I'll personally be doing, but rather the excitement of the place as a whole. There's a tremendous atmosphere of change at Princeton right now -- in the Administration as well as among the students. Having a chance to help plan such changes would be enormously interesting as well as simply enjoyable."

But the spirit of change among the students will present some challenges Rudenstine won't be able to plan so easily. "There's a new mood of student activism at Princeton." Rudenstine says, and next year he will have to determine much of the University's response to it.

At Harvard, Rudenstine has won the respect of both protestors and Establishment by his spirit of rational, controlled activism. Last October, his timely intervention was credited with helping change the mood of protestors at the Dow demonstration. Grabbing a microphone while the crowd was still holding the Dow representative captive, Rudenstine urged the protestors to reject repressive tactics. Rudenstine's was the first of the "opposition speeches" that eventually convinced the crowd to release its hostage before the "police action and possible violence" Rudenstine warned against could begin.

"In general, I'm very sympathetic with what many of the students are doing, especially since I'm doing many of the same things myself," he says. "At Princeton, I will try to encourage the kind of protest which is constructive."

A smile crosses Rudenstine's face as he realizes that what an administrator considers "constructive" may not coincide with what a protestor considers "necessary." "I have to admit that the possibilities of dealing with the students are terrifying, as well as exciting," he says. "But my hope is stronger than the nightmares."

As she left a Rudenstine Hum 6 section last week, a freshman Cliffie burst out, "I feel all like Diogenes. I've found Truth at College. I've found the Honest Teacher."

The reaction at womanless Princeton may be less exuberant. But Rudenstine will probably get used to it.