Cambridge literati tend to forget that selling used books is basically just another business. There are plenty of things to remind them: the way all the books in Pangloss are catalogued in one binder for easy reference, for instance. Or the way Harvard Book Store absolutely and unflinchingly charges half the original price for all of its used paperbacks. But give them a place like the Starr Book Shop with its crazy castle exterior and its piles and shelves of musty, dust-covered, unalphabetized books, and their romanticism goes wild. Visions of Bloomsbury circles and artistic Jamesian bookbinders flit through their minds. No doubt they imagine the booksellers themselves -- the tall, thin man with the distinguished-looking, white goatee, and the heavier-set, clean-shaven man with the ever-present pipe--as the central figures in a coterie of important literary Bostonians.

So much for the romantic image. In fact, Milton Starr (he's the one with the pipe--the other is his assistant, Ernest Morrell) is the epitome of the self-made businessman. He always refers to selling books as "the business."

Mr. Starr grew up in Medford, one of four boys in a family of seven. Two of the brothers are now booksellers. A few years after Mr. Starr took him into the business, his brother started his own store in Boston, and two are surgeons. Mr. Starr's father and grandfather were both book-binders. "Maybe that's how I got into this business," he muses.

Mr. Starr founded the Starr Book Shop forty years ago, in the store space that now houses Cahaly's. That makes his shop the oldest one of its kind in Cambridge. Eighteen years ago, he moved to his present location in the Lampoon castle, where he maintains friendly relations with his neighbors. "They buy humor books here," he says. "And they invite me to their parties. Yeah, I go," he adds.

From virtually nothing, Mr. Starr has built up a business that caters to libraries and collectors around the world. He picks up a fist-full of order forms from his cluttered desk and waves them at me. "See, this one's from Germany," he says. "And these are all from Canada." Many of his customers are people who have seen the catalogue he sends out, or who've heard of him through the trade journals. But he also makes a lot of contacts through visiting professors who come to Harvard from other countries. That's one reason he thinks. Cambridge is about the best place to have a book store like his.

In addition to his mail-order work (that's what he does all day,, when he's sitting at that desk), Mr. Starr does a thriving off-the-street business. That accounts for about half his sales, he estimates. For forty years Harvard students have bought his books. Bate, Alfred, Perry Miller--they were all his customers as undergraduates. He remarks that students used to buy more books than they do now-- "not what they needed in their courses, just what they wanted to own." He gets a lot of outsiders, too, many of them attracted by the unusual building. During the Roosevelt administration, Vice President Henry Wallace came in to buy some books by an obscure Italian writer. And just the other day, he sold something to one of the Watergate reporters from the Washington Post. Does he always recognize the famous people who come in? "Oh, I usually recognize them," he says. "And they tell you who they are, too." One of his more famous customers is John Updike, who bought a first edition of Johnson's dictionary for $1200.

Mr. Starr has taught himself to be an expert on rare and expensive books. "Everything you learn is by mistakes that you make," he says. "I could write a book on the things I've given away at low prices." He tells one story about the time his brother sold a William Blake book to a Harvard student. Inside was a piece of paper that said simply. "There will be a sale of William Blake prints on Wednesday." "Can I keep this?" asked the student, and his brother said, "Sure." The piece of paper, which had a watermark date of 1810, turned out to be one of three in the world, and the student sold it to the Houghton Library for $600.

Another time, Mr. Starr sold a first edition of Emerson's early poems to a New York dealer for $75. He thought he was getting a pretty good price, since the auction listings had that edition priced at about $50. But the dealer sold the book to another dealer for $600, and he turned around and sold it to Harvard for $2000. "That's because it was a presentation copy to Henry Ware," says Mr. Starr. "He was Emerson's minister, and he almost convinced Emerson to go into the ministry." Mr. Starr is full of biographical information about American literary figures, and when you ask him how he learned it, he says: "Well, it's from being in the business."

One thing Mr. Starr really likes about the business is that he never knows what new bargains he's going to find from day to day, or where he's going to find them. Somebody just calls up from an estate or library sale, and he goes out to take a look. One day he went to a sale at the Roxbury annex of the Boston Public Library. When he came back he told his brother, "I bought 30,000 books, and I bought the building, too." "Are you crazy?" said his brother. The building was the Fellows Athenaeum, where Edward Everett Hale was the first librarian. George Santayana lived next door to it and studied there. Mr. Starr used it as a warehouse until he got tired of patching up broken windows, and then he sold it.

People come into his store asking for an amazing variety of out-of-print books ("O.P. Fiction," as it says on his card), and he can tell them immediately what he has and where it is. "A history of music by Lang?" asks one woman. "I used to have a few but I sold them," he says. "Do you have anything on horses?" says a young man. "Downstairs, all the way to the back and to your left," Mr. Starr answers. Does he know where every book is? "Of course." How does he remember? "You have to have a good memory in this business."

He knows about quality, too. A student buying a $25 set of Thackeray wants to know if the paper will last well. "Oh, the paper will last longer than you'll last," says Mr. Starr. The student starts making out a check (Mr. Starr never asks for identification with checks--surprisingly unbusinesslike) and asks, "Starr Book Shop?" "Yeah -- INC," Mr. Starr spells out, with something like subdued pride in his voice.

The book business may be just another business, but for Mr. Starr it's the only one. Not just because it enabled him to put two kids through college, either. "It's the most interesting business you could possibly be in," he says.