On Friday, the Charleston Library Society is hosting a fundraiser for Patrick McMillan and the South Carolina Botanical Garden.

This past summer, floods wiped out the garden, and McMillan, a Clemson professor and host of an ETV nature program, is trying to rebuild it.

The Library Society offered to host the fundraiser because, well, that’s what they do.

But before McMillan rolls into town, the library will host novelist Cassandra King on Tuesday, journalist Elizabeth Becker on Wednesday, Baroque Night (also on Wednesday) and a couple of seminars on the ancient trade route between China and Rome.

So basically, it’s a typical week for the Library Society.

In the past three years, the library — one of the nation’s oldest subscription libraries — has quadrupled its membership. A decade ago, it might host eight or 10 events in a year. Now it holds more than 140.

The Charleston Library Society has done nothing less than reassert itself as a cultural force in Charleston, and a lot of folks are glad to see it.

“They are not just an archive or repository for information,” says Scott Watson, executive director of the city’s Office of Cultural Affairs. “It’s great to go in there for an event and see the turnout they get. They are hitting a market demand.”

And what else would you expect from the city’s oldest cultural institution?

As Watson says, you can live in Charleston your whole life and not know what kinds of treasures reside at 164 King St.

Later this month, the Naval Order of the United States is visiting the library because they all want to see John Paul Jones’ written outline for the Navy.

Yes, it’s in the library vault.

In February, Sandra Day O’Connor is coming in to see the letter that John Marshall wrote on the day he inaugurated Thomas Jefferson. Marshall was, well, a little wary.

Those are just a couple of the many things the Library Society has amassed in its 265-year history. This new ambition, however, was acquired a few years back when the board hired Anne Cleveland as executive director.

A former educator, Cleveland has changed the pace of life at the Library Society so much, and spends so much time there, that her husband, Will, jokes that she needs to list 164 King as her residence.

Cleveland is too classy to take all the credit herself.

“I don’t think I’m doing anything new — just bringing it back to what it was,” she says. “It was the cultural and intellectual hub of Charleston for 200 years.”

And it is again.

Watson says the library has been a great partner for the city, hosting Piccolo Spoleto events and teaming up with the Gibbes and the Preservation Society.

And, he says, the Wide Angle lunch lecture series has lured a lot of people to lower King. Come in and eat, listen to a writer. Or a journalist. Or a botanist.

The library has held mixers to draw in a younger crowd, which was once a challenge. But now that the scope of the library has expanded, you’re as likely to get a “Beatles, Bach and Beer” concert as you are an evening with “Presumed Innocent” author Scott Turow (that’s next month).

Every week there is something going on in Charleston designed to get people standing around in a park somewhere eating or drinking. That’s all fine, but this city deserves a little something more. And we have it.

The Charleston Library Society is feeding the city’s mind, its soul.

For bibliophiles and students of history, the Library Society has always been a treasure — one of Charleston’s best-kept secrets.

Luckily, it’s not so much of a secret anymore.

Reach Brian Hicks at bhicks@postandcourier.com