Origin of a Collector : It started when he was 10. From then on, Warren David Mohr’s obsession with all things Darwin grew. Then he gave it all away.

SAN FRANCISCO —  He calls him Charlie. Sometimes just Chuck. Once, in Corsica, he called him Carlos--as in, “ Prego, senor . Would you have any books by Carlos Darwin?”

Had time been kinder, Warren David Mohr--perhaps the greatest private Darwin collector of all time--and Charles Robert Darwin, perhaps the greatest zoologist of all time, would have been contemporaries.

“I call them ‘The Odd Couple.’ One of them is living and one of them is dead,” says Mohr’s wife, Betty. “Still, they are absolutely inseparable.”

Until now.

After six decades of feverish browsing and careful buying, of crisscrossing continents to track down every Darwin work from “Origin of the Species” to “The Formation of Vegetable Mould Through the Action of Worms,” Mohr has given it all away.

And with it, his heart.

“Don’t think for a moment there haven’t been tears,” Mohr says with a pout. “I can’t help it. I miss him. I miss my Charlie.

In a tear-soaked ceremony last month at the Huntington Library in San Marino, the 71-year-old collector dedicated to posterity about 1,600 Darwin books, caricatures, engravings and photographs. According to rare books curator Alan Jutzi, their value is inestimable, particularly to science historians.

Among them are volumes signed by the author for special friends, privately printed books for family members, and one book bound with an imposing gold crest and dedicated to a member of the British royal family. Indeed, when it comes to Darwin collecting, Mohr’s single greatest rival is a woman Mohr calls “Lizzie.” And the Queen of England isn’t about to let him buy her three Darwin manuscripts. He knows. He’s tried.

If Darwin was, in the words of his biographers, “a man of enlarged curiosity,” Mohr is a man of enlarged energy. That’s not to say he is incurious. But how else does one explain a lifetime of global and often solitary sleuthing with just one goal--understanding Darwin?

“Charlie only wrote 16 books, you know. But that never stopped me,” Mohr boasts. “Oh, how I loved to present my books at Customs and the Customs man would say, ‘But, sir, you have bought 20 copies of the very same book!’

“ ‘Of course, I have. Of course, I have,’ I’d laugh. Aha! Little did they know that each of the books was different--some quite subtly, others quite grandly because Darwin wrote and rewrote with each edition--new forewords, new introductions, new opinions to show the terrible controversy that followed each new discovery.”

Unlike Mohr--who is, by most accounts, including his own, one of the happiest men on earth--Darwin was among the most troubled. Apparently as a result of a bug bite on his historic voyage as naturalist for the HMS Beagle, Darwin suffered a debilitating stomachache for the last 30 years of his life.

When he wasn’t at some spa or sanitarium seeking a cure or at home with his eight children, Darwin was dodging angry crowds of creationists and the entire Church of England, who wanted his head for crimes against society. His chief crime, of course, was to suggest that plants and animals had evolved from a few common ancestors.

In the Victorian era, Darwin’s ideas--and therefore, his books--were intellectual dynamite. They shocked and distressed the people of his day, most of whom believed each species had been created by a separate divine act.

At first, even Darwin felt badly about his work. “It is like confessing to a murder,” Darwin said when he was forced by colleagues to reveal what he knew: that humans were indeed descended from headless, hermaphrodite squids.

But it wasn’t squids or even monkeys that attracted Mohr to Darwin. It was Mohr’s desire at the innocent age of 10 to produce “the best darn orchids in San Francisco.”

Unable to get the books he needed in the United States, young Mohr started corresponding with a London dealer who offered him a book by another great lover of orchids.

The book turned out to be a rare first edition of “On the Origin of the Species,” Darwin’s seminal tome on how we all began. The dealer wanted $45 for it, far too much for a 10-year-old--even this one, a fourth-generation San Franciscan whose mother was a library commissioner and philanthropist and whose father helped build the Bay Bridge.

“So I appealed to my father for a loan,” Mohr recalls. “He refused. So I went to my grandmother for an advance against my Christmas present. She gave me the money and since it was mid-year, by the time Christmas came round, she forgot.”

The book, bound in the traditional green leather of Darwin’s 19th-Century publisher and now worth tens of thousands of dollars, stands as “the pinnacle of the collection,” Mohr says.

But one sunny spring morning, Mohr’s book from childhood joined hundreds of others for one last voyage. A rose-colored van from the Pink Transfer Company pulled up in front of the Mohr home to carry his collection 400 miles south to its new quarters behind glass in an environmentally controlled chamber of the Huntington Library. A few of the works, including Darwin volumes illustrated with William Blake drawings, will go on display June 6 for library members.

Back at the home Mohr bought years ago to accommodate his Darwin obsession, the collection-less collector solemnly guides visitors to a spacious sky-lit hall on the third floor. “Here, look here. You can still see the impressions in the rug where Charlie’s bookcases used to stand. Couldn’t bear to see them empty. Had to have them all torn out. Can’t begin to describe the trauma of it all.”

But Mohr’s wife, whom he dramatically calls Lady Elizabeth, is recovering nicely, thank you.

“Trauma? What trauma? I’ve had 32 years looking at dusty books and cooling my heels outside shops in London, France, Corsica and who-knows-where, waiting for Warren to lug another stack of books back to the hotel, where he’ll stay up all night reading and fussing over them,” she says. “At least we can get on with our life now.”

Soon, the couple will begin with a long-overdue vacation in France. Or maybe not.

With Betty off packing their bags, Mohr whispers: “Lady Elizabeth, she’ll kill me, but I must tell you, once we get to France, I’m going off to Prague. Briefly, very, very briefly. I must, you see. There is an edition I really must have. It’s in Russian, you understand. . . .”