To this day, few works in science evoke as passionate a response as those of Charles Darwin.
It's 150 years since the naturalist's seminal work On the Origin of Species was published and with next week marking the 200th anniversary of his birth there's set to be a frenzy for all things Darwinian.
Darwin's theories were vilified by some – notably by the Anglican Bishop Samuel Wilberforce – but he was lionised by Victorian scientists. Today, academics, philosophers and theologians largely agree his greatest achievement lay in his ability to communicate his reasoned, revolutionary ideas plainly. His works still cause controversy few other scientists have provoked.
In the autumn of 1859, awaiting the publication of Origin, in ill health, and ensconced in Ilkley "to take the waters" at White Wells and nearby Wells House, a 50-year-old Darwin literally sweated on the eve of both notoriety and fame.
As he convalesced at Ilkley, some wonder if more out of nervous anxiety than a true malady, experts say his sense of foreboding, and perhaps intimations of mortality, must have been palpable.
In a series of letters written from the Yorkshire market town to his friends, biologist TH Huxley, geologist Charles Lyell, and botanist Joseph Dalton Hooker, he tentatively awaited reviews.
"I have been here nearly a fortnight, and it has done me very much good," he said in one. "If I can keep up my spirits, I shall stay eight weeks here and thus give hydropathy a fair chance. Before starting here I was in an awful state of stomach strength, temper and spirits.
"You cannot think how refreshing it is to idle away the whole day, and I hardly ever think in the least about my confounded Book, which half killed me."
Just days later, the Rotherham-born botanist HC Watson wrote to Darwin at Ilkley suggesting Origin... "would become an established truth in science", though it would "shock the ideas of many men". Darwin replied saying he feared reviewers would find his conclusions "abominable".
Richard Carter, founder of the Yorkshire-based Friends of Charles Darwin (FCD), has no doubts as to Darwin's trepidation and of his subsequent stature.
Carter, from Hebden Bridge, whose society now has more than 2,000 members worldwide, successfully campaigned for six years to have Darwin commemorated on the 10 note.
He says: "Darwin was already respected as a scientist before the publication of On the Origin of Species thanks mainly to his Beagle voyage, his geological work, and his eight-year study into barnacles.
"But, clearly, it was Origin... that made him into a household name and upset a lot of people. Darwin was never really a devil's chaplain in his own right. He did not court controversy, he left that to his supporters. Today, he is recognised as the greatest biologist who ever lived: the man who came up with a theory so simple that a child can understand it, but a theory so powerful that it explains the whole of the living world.
"In many people's opinion, it is quite simply the best idea anyone ever had."
The seeds of the Darwin's evolution theory were sown during his five-year trip on HMS Beagle. Spotting differences between mockingbirds living on the various Galapagos Islands, he realised that contrary to popular thinking species could and indeed had adapted to different environments.
"Darwin was a capable geologist and superb botanist," says Peter McGrath, founder of The HMS Beagle Project, from Whitby. "He was working at a time where science was wide open for all manner of discovery, but it still took a brilliant mind to look at the Galapagos mockingbirds, throw away all his education and preconceptions and realise that they 'undermine the stability of species' as he wrote in 1835. That was Darwin's great achievement."
This was no overnight Eureka moment and had it not been for a rival in the field, Darwin may have further delayed publication of the groundbreaking book.
"It was a letter from an acquaintance, Alfred Russel Wallace, who had independently come up with pretty much the same Natural Selection theory, which finally forced Darwin to go public with his theory," says Carter.
"Had Darwin not existed, we would still have a theory of evolution by means of Natural Selection. But because he spent 20 years thinking about his theory before publishing it, by the time he went to press, he could make a pretty unassailable case." Nowadays, the fact that organisms evolve is uncontested in scientific literature and evolution is widely accepted by scientists and many churchmen.
However, it remains a contentious concept for some "creationist" groups who have long shared the belief that God created the universe and everything in it.
A Mori poll three years ago estimated that less than half the UK population fully accept the theory of evolution and last month it emerged a third of all science teachers think creationism should be taught in their lessons alongside the Big Bang theory.
"Some people just can't be convinced," says Jerry Coyne, author of Why Evolution Is
True? "I once gave a lecture to a bunch of businessmen about why scientists believe in evolution. At the end one of them came up to me and said, 'You know I found your evidence very convincing. But I'm still not convinced'. No amount of evidence would ever convince them. That's the nature of faith."
The Church of England last year made a well-publicised formal "apology" to Darwin's memory and legacy and has set up a special section of its website for the forthcoming anniversary. The Rev Dr Malcolm Brown, CofE Director of Mission and Public Affairs, asserts good religion needs good science.
He says: "When a big new idea emerges which changes the way people look at the world, it's easy to feel that every old idea, every certainty, is under attack and then to do battle against the new insights.
"The Church made that mistake with Galileo's astronomy, and has since realised its error. Some Church people did it again in the 1860s with Charles Darwin's theory of natural selection. So it is important to think again about Darwin's impact on religious thinking, then and now.
"'Darwinism' has become something bigger than Darwin's own theories, and raises many moral questions.
"This doesn't make the Church of the 1860s right to have attacked Darwin, but it does suggest that the question is deeper than deciding whose side you would have been on in that historic debate between Samuel Wilberforce, Bishop of Oxford, and Darwin's supporter, Thomas Huxley."
No doubt the debate will continue to evolve over another 200 years – as will, slowly, mankind. Into what, is another question, perhaps beyond even Darwin's genius.
People can join the Friends of Charles Darwin at http://darwin.gruts.com. A replica Beagle will spend the next three years circling the world in Darwin's wake and more information on this is available from www.thebeagle project.com.
A NEW SPECIES OF SCIENTIST
Charles Darwin was born in Shrewsbury, Shropshire on February 12, 1809.
In 1825, he began studying medicine at the University of Edinburgh but didn't feel suited to it. He later enrolled on a theology degree at Cambridge University but enjoyed collecting beetles more.
Darwin joined the exploratory voyage of the HMS Beagle around South America, Australia, New Zealand and the South Pacific in 1831. During the five-year trip he sent home 1,529 species preserved in spirit and 3,907 labelled skins, bones and other dried specimens.
One specimen comprised the leftovers of his 1833 Christmas dinner, in which he had accidentally eaten a new bird species.
He returned to Cambridge in 1836, and spent the next two years working on material gathered during the Beagle voyage.
On January 29, 1839, Charles married his first cousin Emma Wedgwood, the granddaughter of pottery manufacturer Josiah Wedgwood. He had put some thought into the decision to wed – when he returned from the Beagle voyage he compiled a list of the advantages and disadvantages of marriage, concluding that a woman would be a better companion than a dog in his old age.
The couple moved from London to Down House, on the North Downs of Kent, in September 1842. They had 10 children, three of whom died before reaching adulthood. Their deaths prompted Darwin to fret that inbreeding – the result of his marrying his first cousin – was to blame.
The family kept horses, cows, pigs and poultry – and Darwin studied domestic pigeons to provide evidence for his theory of evolution by natural selection, building a pigeon house in his garden in 1885.
Last month a letter written by Darwin in which he railed against stupid questions being asked by "half the fools throughout Europe" was sold in Somerset for 2,100.