Nathan Walker took his final exam last week but, being a student at St. John's College, he didn't put pencil to paper: He sat down in the college library and had an hour-long chat with four college tutors about Rousseau, Hobbes and the nature of man.

No big examination hall, last-minute cramming, soft-lead pencils and "A, B, C, D or all of the above" multiple-choice challenges for Walker and other "Johnnies" seeking degrees. No grades, either.

By the time the students have finished four years of reading and debating the "great books" at the small liberal arts college, college officials reckon that they are worthy of a being dubbed bachelors of arts if they are capable of intelligently discussing their last essays.

All 404 students at St. John's College here -- it has a sister campus in Santa Fe -- study the same great books. The literature, philosophy, science, mathematics and language works range from Homer and Plato in the first year to Tolstoy, Kierkegaard and Darwin in the fourth year. Even without written exams, the course is rigorous enough to persuade 40 percent of students to leave before they've finished.

But those who make it through four years typically are able to talk intelligently about the experience, school administrators say.

Last week, Walker, a 21-year-old Californian, walked into the King William Room of the college library dressed in an academic gown. He was introduced to three gowned tutors, as professors at the school are known, by another tutor known as his "presentor."

A dozen of his friends and supporters were in the book-lined room to observe; one placed a small spray of flowers in front of him. The tutors had already read his essay on Rousseau and Hobbes, but, following tradition, Walker started off by reading a small summary of the essay for the benefit of the guests.

Then the tutors started asking questions. Robert Williamson, who led the examination, asked if Rousseau's theory of education would require the student to withdraw from society. And how practical was it all, anyway? Could Hobbes and Rousseau talk to each other without getting angry?

"That would be really tough," said Walker, as the group launched a discussion of how Hobbes and Rousseau would differ.

The questioning rapidly became lively chatter, and sometimes the tutors asked each other questions rather than Walker. It certainly wasn't a grilling. When Walker's theories were challenged, the questions were usually cushioned in the conditional tense: "There's something that I would be disturbed about," said tutor Jon Lenkowski at one point.

Tutor Susan Fain apologized for asking personal questions, and then asked Walker why he chose to dicuss Rousseau and Hobbes in the first place. Walker talked about his interest in the differences between the philosophers.

But then it was suddenly over. "We have used up our time," Williamson said abruptly. "Thank you."

With that, the tutors retired for a private talk about Walker, and Walker retired for a beer.

Afterward, Walker said he thought it went well. He said a friend watching the exam reported that he "threw the logos excellently."

Logos? "It means reason -- reason, speech, discourse. It means a lot of things," said Walker who, like other St. John's students, has studied his fair share of Greek.

Jennifer Flynn, a senior who watched Walker's exam, said she thought it a good, lively discussion and a fine way to have a final exam.

"I went to the University of California at Berkeley before I came here," she said, "and we had final exams that were so impersonal."

"This is the test of your lifetime, but you just have a conversation with them," Walker said. "I enjoyed the conversation. It felt relaxed."

Walker, who is off to teach English in Tokyo at the end of the school year, said the education has given him no special vocational skills, "but I have a good set of equipment. I've had four years of math, science and language, and that's a pretty round education."

"The classroom procedures are based largely on discussion," noted tutor Robert Williamson. "What the examination stands for, I think, is a kind of culmination of the student's growing ability to perform well in a discussion -- to talk about something he or she has thought about at considerable length."

College Dean George Doskow acknowledged that the final examination "is not something that people fail."

Every two or three years, he said, "someone freezes and their mouths won't move," in which case they are given a second chance, usually in private.

For most of their time at St. John's, Doskow said, students are evaluated through oral exams, and it seems right to make the last one "more public and ceremonial. Although we call them oral exams, it's clearly much more of a discussion. It's public mostly so that their friends can come. It's an occasion for celebration. It's just a nice happy ending to their careers here."