NAHANT – For more than 21 years, Library Director Dan deStefano has been as familiar a fixture in the library as the building’s glass floor.But now, he said, it’s time to write, not just shelve, his books, as he announced to library trustees Wednesday night that he plans to retire from his position at the end of December due to health reasons.”When your health starts to fail you and you’re in a building that’s nothing but stairs ? I would rather people say, ?Gee, it’s early for him to retire,’ rather than, ?It’s about time,’ or worse yet, ?It’s past time,'” deStefano, 62, said Thursday. “I’ve tried to do a lot for it and there’s more I’d like to do. Some of the goals I’ve made, some of them I didn’t. But that’s just life.”DeStefano said that he has suffered from kidney disease for 20 years and that the accumulated treatments and medication have weakened him too much to continue at the library every day. He said it was a very difficult decision, particularly because the library itself is so unique – for better or for worse.On the negative side, the 1895 building requires a lot of upkeep, which deStefano said was getting beyond his capacity. He noted that the original architects suggested in a report that the building would need to be expanded in 1945 to accommodate the town’s growing population, book collection and town artifacts.But that expansion never happened, and now “there is a huge attic and it is filled with stuff,” said deStefano.While many of the most valuable items have been taken to the historical society – which deStefano said leaves him free from worrying about how to prevent them from being rained on each spring – much remains, and the stairs were proving an unwelcome impediment, deStefano said.But the library’s small size and patron population also provided many opportunities. DeStefano recruited two public works employees to pick up card catalogs from MIT, and he and his wife and daughter replaced the catalog over a weekend.He researched and developed a new exhibit for the library’s collection of Native American stone tools, and he developed programming that featured many of the community’s talented citizens.He also worked hard to develop programming for schoolchildren.”That’s the future,” he said. “The library is really the collections and the people. The building is just the box you put it in. That may be heretical to some, but while the window dressing is nice, in the end, the library needs to accomplish its mission, and that mission is education.”Library Trustee Chair John Welsh said that accomplishing this mission was deStefano’s biggest accomplishment.”He had such a commitment to the library as a place that transmits knowledge so that people can be a functioning part of a democracy ? I hope we can find somebody else with that commitment,” Welsh said. “Although Dan is irreplaceable, we hope to find somebody with equal enthusiasm and intelligence.”Meanwhile, deStefano said that he has plans to keep busy. He has just completed his first novel, “Seeress,” which is set in the Cretaceous Era and features a race of intelligent dinosaurs. He also plans to make finishing touches to a children’s book he wrote. He also said he plans a book about being a librarian. So, although visitors in January may not find deStefano behind the library’s desk, they’ll be able to locate him on the shelves.