Libraries are a haven for many. Rarely are their doors closed to anyone.

Unless you're a free-roaming cat.

This sign was on the door of the library for Macalester College library in St. Paul, Minnesota, and as good as the sign is, there's an even better story behind it.

A serious case of wanderlust

In his early years, 3-year-old Max spent a fair bit of time on the streets, according to the Washington Post. It wasn't until last year that he was adopted by Connie Lipton, but finding a forever home wasn't going to stop Max from exploring his new domain: Macalester College, near where Lipton lives.

And so Max became something of a fixture. He crashed events on campus, hung out with students on the quad and likely would've become a visiting professor of some sort, given the opportunity.

"We've had multiple calls because his phone number is on his tag," Lipton told the Post. "He's a funny guy. He loves people. He loves to socialize — with groups."

As accepted as he was around the place — big cat on campus, indeed — Max's forays into the college library weren't particularly welcomed. In addition to zooming by students who were carrying books or trying to study, one library employee is very allergic to cats. Plus there were concerns about Max getting locked in the library overnight.

Oops Max was caught on camera as he sneaked into the library about a month ago

A post shared by Max the Cat and Gracie (@cool_cat_max_and_gracie) on

Banished from the books and elsewhere

As a result, Max was banned with a handwritten sign taped up in late October. But the sign that went viral and captured the internet's attention happened more recently.

It was created by Christopher Schommer, a library employee. He returned to work after 12 weeks of parental leave, so he'd missed some of the Max saga. The cat illustration was taken from The Noun Project, and Schommer and the illustration's creator, Gamze Genc Celik, are taking Erin McGuire's tweet to heart and turning the sign into a children's book.

"I'm sure 200 people are also doing the same thing," Schommer joked to the Post.

As McGuire's tweet went viral, internet users rushed to support Max's interest in reading ... or at least his interest in napping in the stacks.

Alas, Max has not only been banned from the library; he's been banned from roaming. A construction project is underway on campus, and Lipton is naturally worried that Max's inquisitive nature might get him stuck.

That doesn't mean he's still not getting to go outside, however. Lipton purchased a leash and harness so she can take Max on walks.

"He's going crazy. He cries and howls and paces around, looking out the windows," Lipton said. "I'm really hoping he takes to walking on the leash. Then I can just walk him over there and he can still see his peeps and have his social life."