Nancy Bass does not look like a bookworm. But she reads more than most, and, as the co-owner of New York’s Strand Book Store, she spends every day in bookworm heaven.

Founded in 1927 by Benjamin Bass, Ms. Bass’s grandfather, the Strand is the world’s largest secondhand bookstore. It was named after London’s book district, and after The Strand magazine that published some of Arthur Conan Doyle’s Sherlock Holmes stories. Originally opened on the stretch of Fourth Avenue known as Book Row, the store was moved to 12th Street in the mid-1950s by Ms. Bass’s father and Strand co-owner, Fred Bass.

Ms. Bass has now worked full-time at the Strand for 16 years. “We work really well together with my father,” she says. “My dad loved working here, and I think I just picked it up.”

How could she not? At Strand, the books, measured standing front-to-back, stretch out to 18 miles. It buys estates that sometimes include books bought at the store decades earlier. People can bring in books to sell for cash. Early review copies give an avid reader as much as six weeks’ head start on a book’s actual publication.

The Strand’s basement houses the science section and early review copies. Shelves on the main floor are crammed with books on history, literature, and fiction. Some years ago, the Strand acquired a quarter of a million art books when it bought the Hacker art bookstore. The store was later closed, and the art books are now on the Strand’s newly opened second floor, along with children’s books and a children’s reading area with pint-sized tables and chairs. A small space nearby may soon house a coffee bar – if book spread does not claim it first.

The rare book department on the third floor is probably the largest in New York, and has the musty smell that is catnip to bibliophiles. A vault holds the rarest of the rare. The store’s inventory includes incunabula (early printed books, dating back to 1500 or before), with the oldest a leather-bound volume with bronze clasps that is an intricately decorated commentary on the Psalms printed in 1480 in Cologne, Germany.

A Shakespeare Second Folio from 1632 costs $125,000, while a limited edition of James Joyce’s Ulysses, illustrated by Henri Matisse and signed by the author and illustrator, can be had for $35,000. A volume of Fellini screenplays, adorned with Fellini’s signature and a pen-and-ink self-portrait in tails and top hat, costs $1,000.

Strand employees are there for the love of books, and stay for years. Love of books is the main criterion for hiring, says Ms. Bass, and the employment application includes a literary matching test. Beware the trick entry if you apply, not all entries have a direct match.

Some of the Strand’s more unusual bargains include books by the foot. They are sold to decorators and set designers as background, and are immensely popular. Strand books can be ordered at www.strandbooks.com, and the mail order business is booming.

Browsing at the Strand you may run into Umberto Eco seeking inspiration, but also Spike Lee, Shimon Peres, or Barbra Streisand. Jackie Kennedy Onassis and Andy Warhol were regulars.

Book signings are popular. At 6 p.m. on Friday, Christo and Jeanne Claude, the “wrap” artists festooning Central Park with saffron waves of fabric, will be in the store signing copies of their book, “The Gates.”

When next you feel the need for spiritual renewal, skip yoga and head to the Strand. Milton was right, “A good book is the precious life-blood of a master spirit.”