Teddy Roosevelt knelt in the grass, raised his rifle and eyed the lion that was charging straight at him.

The animal was a “splendid old fellow,” Roosevelt would later write. “A heavy male with a yellow-and-black mane . . . burly and savage.” The lion raced closer, its ears laid back and fierce, guttural grunts echoing from deep within its throat.

It was June 1909. The former president was three months out of office and two months (and several slain lions) into an East Africa trip aimed at collecting specimens on behalf of the Smithsonian. But he had yet to capture a creature as large and impressive as this one. This was a scientific expedition, but there was no denying his motivation was partly ego: He really wanted to bag a big lion.

Roosevelt took aim and fired.

“The bullet went as true as if the place had been plotted with dividers,” he recalled in his account of the expedition, African Game Trails. “The blow brought him up all standing, and he fell forward on his head.”

As a storm gathered in the west and the red sun sank low over Kenya's Sotik plain, Roosevelt and his companions set about skinning the lion. Then they brought the pelt back to camp, boxed it up with hundreds of other specimens, and shipped it off to Washington, where taxidermists at the U.S. National Museum were waiting to help bring it back to life.

On an afternoon last month, the lion stood in the middle of a windowless room at what has become the National Museum of Natural History, its right paw extended outward, its head held high. It's been out of public view for two decades, but now the museum is preparing the lion to go on display in March. It will be part of an exhibit of highlights of the Smithsonian's collection.

The past century has taken a toll on the majestic creature. The lion's tawny fur is crushed in places, and his rumpled mane gives him the appearance of having bed head. A portion of his ear is clipped, chunks of fur are missing, and his glass eyes have gone foggy with age.

Conservator Ron Harvey surveyed the mount, assessing the damage, deciding what to repair and what to leave as is.

“I want him to look his best,” he explained. “But it is 100 years old. I want to maintain that sense of history too.”

The job of a natural history conservator goes far beyond simple aesthetics. Harvey must maintain the specimen's scientific usefulness, ensuring that it can be studied by future generations. He also wants to preserve it as a historical artifact — an object that can tell us about our past and its own. When museum visitors look at this mount in six months, Harvey hopes they'll get a sense of how it got to the museum, what it meant when they arrived, what it stills mean today.

“What story did this lion and Roosevelt want to tell us?” Harvey wondered. That's what he aims to conserve.

In his final days in office, facing the fact that he was about to become the youngest-ever former president, Roosevelt was grappling with what to do next. He knew he didn't want to stay in Washington after the inauguration of William Howard Taft, a fellow Republican and his chosen successor. Pundits were already lambasting Taft as Roosevelt's puppet, and a New York Times article from the time claimed that Roosevelt's “express desire is to get away as soon as possible so as not to embarrass Taft in his new office.”

Then a fateful conversation with Carl Akeley, a biologist and taxidermist who was laying plans for a year-long African collecting expedition on behalf of the American Museum of Natural History in New York, rekindled Roosevelt's childhood dream of becoming a naturalist.

The trip was announced on Election Day: Roosevelt, his son Kermit and three scientist friends would spend 11 months in Central and East Africa, surveying the landscape, observing the fauna and collecting specimens for research. His offering to the Smithsonian would include not just skins for taxidermy, but also skeletons, bugs, plants and meticulously documented information about the animals' habitat, biology and behavior.

“As you know, I am not in the least a big game butcher,” he wrote to Smithsonian Secretary Charles D. Walcott. “I like to do a certain amount of hunting but my real and main interest is the interest of a faunal naturalist. Now, it seems to be me that this offers the best chance for the National Museum to get a fine collection . . . and looking at it dispassionately, I believe that the chance ought not to be neglected.”

That last sentence was a nod to the fact that Africa's big mammals — and the environments they inhabited — were swiftly vanishing. By the turn of the century railroads crisscrossed what was then the colony of British East Africa, and farmers had fenced off the land. Overhunting, much of it for sport, was pushing many creatures to the brink of extinction. Roosevelt had seen the same thing happen in the United States a generation earlier: the near-extinction of the bison, the actual demise of the passenger pigeon, the transformation of the landscape.

He viewed his expedition as an act of conservation. If the world could read about his encounters with creatures like the lion, if people could see the impressive animal for themselves, perhaps they would be motivated to preserve nature. And if legal protections did come too late, at least he would have captured a snapshot of this wilderness before it was lost.

“He was acutely aware of wanting to document something of the privileged time in which he was alive,” says Darrin Lunde, a Roosevelt biographer and collections manager for the division of mammals at the National Museum of Natural History. “Because he knew that in 100 years, East Africa would be like the American West. There wouldn’t be an opportunity for people to go out and collect like this again.”

Predictably, the plan raised a hullabaloo at home. Newspaper reporters clamored to be allowed to accompany Roosevelt on the safari (he forcefully declined). The Chicago Tribune ran a cartoon showing a herd of wild animals racing in the direction of a sign saying “to the tall grass.” The caption below read: “When the news of President Roosevelt's visit reached Africa.”

Critics assailed the expedition as a glorified trophy hunt.

“He is a game butcher, pure and simple and . . . his interest in animals lies chiefly in the direction of blood, butchery and brutality,” nature writer William J. Long told the New York Times. “The only thing we will get out the much-heralded trip will be some more hunting yarns and some more skins and bones, of which we already have too many. The only one who will ever learn or teach anything of value is the man who studies the living animal, not the man who gloats over a dead one.”

The debate over the relationship between killing and conservation still rages today. Think of the outrage over trophy hunters who pay hundreds of thousands of dollars to conservation organizations and wildlife preserves for the opportunity to kill a single animal, or the recent discussion in the biology community about the risks of collecting voucher specimens from threatened species. The political and scientific reality of big game hunting in Africa and around the world have changed dramatically in the past 100 years. But there is still no consensus about the morality of killing one for the good of the many.

“It's a really difficult question,” Lunde says. “Everyone's got a different opinion about the sequence of events we call conservation. . . . I think a lot of Roosevelt's detractors, they just didn't like the idea of these animals being killed. And that's perfectly legitimate.”

Roosevelt was far less tolerant of those who doubted his motives. In a peeved rebuttal in the magazine New Outlook, he wrote, “I can be condemned only if the existence of the National Museum, the American Museum of Natural History, and all similar zoological institutions are to be condemned.”

By the time it ended in early 1910, the Roosevelt expedition had gathered more than 23,000 specimens for the Smithsonian and documented several new species. Prominent Smithsonian mammalogist Charles Handley, who died in 2000, once called the collection “still the largest and most comprehensive single research collection of East African flora and fauna ever made.”

The big male lion and four of its kindred were displayed in a diorama of a Kenyan watering hole, one of the first exhibits at the newly opened U.S. National Museum. It would remain in the public eye for almost a century, fixating generations of visitors with its serious stare. But in the late 1990s the lion was boxed up and stashed away for a renovation of the museum's mammal hall.

After a two-decade stint in storage, it's about to re-enter the spotlight. The lion and two other Roosevelt specimens — a pair of fantastically absurd shoebill storks — will go on display next spring as part of the museum's “Objects of Wonder” exhibit, which examines the history of the collection. Harvey, who runs a private conservation practice in Maine, came to the Smithsonian for a week to get the trio in exhibit shape.

After consulting with museum conservation specialist Cathy Hawks, he decided to leave the lion's glass eyes — which are cloudy and crizzled from a phenomenon called glass disease — as they are. They're historic artifacts too, after all, and they're suggestive of the lion's old age and impressive backstory. On top of which, it would probably cause more damage to try to take them out.

“What we're trying to do in conservation is preserve and extend the life of . . . this body that has not been sapped of all its knowledge,” Harvey said.

He noted that the specimen has been cited in scientific journal articles as recently as 2010, and that scientists are developing new tools for research all the time. There may be other stories — about lion biology, East African ecosystems, 20th century taxidermy methods — buried inside this specimen, waiting for someone with the right question and the right tools to answer it.

But for the time being, Harvey was focused on aesthetics: broken ear, patchy fur, discolored nails.

“I love what you've done with his hair,” Hawks said on Harvey's fourth day at the museum.

Harvey had spent much of the morning carefully “fluffing” the lion's mane by spritzing it with tiny puffs of damp air. This part of a conservator's job makes him feel more like a celebrity stylist than scientific expert.

“It's hair by Ron,” he joked.

Hawks nodded and said, “He still looks a little sad though.”

Harvey examined the animal; the foggy eyes did give him a baleful look. “Well, if you saw Teddy with a pretty high powered rifle pointing at you, you're not going to be happy,” he acknowledged. “But look at the life he has now.”

Tales from the Vault: Science museums are home to vast research collections, most of which the public never gets to see — until now. Once a month, Speaking of Science will go behind the scenes at our favorite museums to introduce readers to the fascinating objects and people we find there. Read past installments here.

Correction: A previous version of this story misidentified the taxidermist who inspired Roosevelt’s trip. He was Carl Akeley.