Of the more than 14,000 letters Charles Darwin wrote during his lifetime, perhaps the most memorable was addressed to his wife, Emma Wedgwood. The naturalist requested that in the event of his death, she use an enclosed 400-pound check to pay for the editing and publication of a 240-page book on natural selection.
"If as I believe," he wrote in 1842, "my theory in time be accepted even by one competent judge, it will be a considerable step in science."
One of the many treasures on display at the newly refurbished Darwin family home, in the Kent village of Downe, the letter is one more reason that a visit to the naturalist's home is a highlight of any visit to Britain.
You can join the 150th anniversary celebration of the publication of On the Origin of Species at the Down House exhibition. Here you'll learn how his home office nurtured Darwin's revolutionary ideas.
At a time when only 53 percent of Americans and 48 percent of the British accept Darwin's theory of evolution, the Georgian home where he wrote this classic offers an inside look at the sometimes maddening world of science, where it remains possible for a college dropout to change the world.
Not content to rest on the success of The Voyage of the Beagle, a travel narrative of his five-year journey around the globe, Darwin quietly husbanded his scientific depth charge for more than 15 years. Convinced that publishing On the Origin of Species was like "confessing to a murder," Darwin decided to finish it only after he realized that another scientist, Albert Wallace, was advocating the same theory. That gave Darwin the push he needed to complete the book and publish it quickly in 1859.
Today even the most ardent opponent of Darwin's theory, the foundation of modern biology, is likely to be disarmed by a tour of Down House.
"You cannot deny what Darwin did," says curator Annie Kemkaran-Smith. People come here every day to look at Darwin's study, the kitchen where he boiled pigeons with the help of his butler, the garden where he worked with pots of worms, and the study where his children helped him analyze specimens gathered on his Beagle circumnavigation of the Earth.
Like Lincoln, born on the same day as Darwin in February 1809, the naturalist's legacy continues to shape our world. Darwin's self-described "ugly" country house, where he lived with Emma and their children, is the unlikeliest of scientific laboratories. At the center is his study, where he deconstructed the biblical view that the Earth was created in one week and built his thesis that all species are interrelated and that humans descended from apes.
Even critics who question Darwin's legacy or have second thoughts about the origin of species should visit Down House. Here it is possible to follow the journey of a lifetime that led this scientist to lay the foundation for contemporary molecular biology and botany, zoology, genetics, sociobiology and, of course, evolution.
A lapsed divinity student who stopped attending church after the tragic death of his eldest daughter, Darwin was not content to merely challenge Britain's theocracy and scientific orthodoxy.
"Darwin knew a lot of people would find it hard to accept his theory," says Kemkaran-Smith as visitors explore the new exhibitions, including treasures such as Darwin's notebooks, the only 43 surviving pages from Darwin's manuscript of On the Origin of Species, Emma's wedding ring and a copy of Das Kapital personally inscribed by Karl Marx.
"A rare example of someone who could think things through and make connections that other people didn't see, Darwin was never trying to challenge people's faith," says Kemkaran-Smith.
Down House remains today what it was 150 years ago: a place that encourages independent thinking, a beacon for free inquiry and an inspiration for anyone who has the courage to challenge orthodoxy.