J. CAMERON, 1869, VIA WIKIMEDIA

Editor's Note: This article originally appeared in Spektrum, and has been translated from German. We are publishing it as part of our tribute to Charles Darwin on his 200th birthday.

Before marriage, Charles Darwin had confessed everything to her. That he was in the process of rewriting the history of life. That, according to his convictions, all living things descended from a common ancestor. And that species were not to be attributed to God's endless creativity, but were the product of a blind, mechanical process that altered them over the course of millions of years. This alone was pure heresy. Darwin even nursed doubts about the very survival of human beings.

And this man, who had gone around the world once, and was going to marry Emma Wedgwood, did not believe a single word of the biblical story of creation. "Reason tells me that honest and conscientious doubts cannot be a sin," wrote the deeply religious Emma to her betrothed in a cautioning letter in November 1838. "But I felt that it would be a painful rift between us." Charles was supposed to find his way back to the right faith by reading the Bible: "I implore you to read the parting words of our Savior to his apostles, beginning at the end of the 13th chapter of the Gospel according to John," she wrote.

But for Charles Darwin there was no turning back. He definitely assured Emma in his reply that he would take her concern seriously. But in fact he was experimenting at that time with all kinds of heretic theories. "Love of godhood is a result of intellectual organization, oh you materialist!" he confided to himself in revolutionary words in his secret notebook. And although his theories were not yet mature, he was completely aware of their explosive nature: By dissociating intellect and morality from god's power of creation, and attributing them instead to self-evolving forces, Darwin undermined the very foundations of a society shaped by the Anglican Church, with its hopes of eternal life and the omnipresent threat of punishment.

"As soon you realize that one species could evolve into another, the whole structure wobbles and collapses," he remarked. And if man were nothing but a superior animal, where would that leave his spiritual dignity? And if he himself is the product of evolution, then what about his moral accountability to God?

Believe only what is proved
"Charles' confession was a big shock for Emma," explains the science historian John van Wyhe from the University of Cambridge. "On the other hand, he impressed her with his openness and honesty. Nothing would have hurt her more badly than the feeling that her future husband was keeping secrets from her." But Emma's worries over the well-being of Charles's soul could not come in the way of her wedding at the end of January 1839. His habit of "never believing anything till it is proven" had apparently prevented him from "taking into account other things that cannot be proved in the same manner, and which, if they are true, would probably go far beyond our power of imagination," she complained in another letter. Emma's worst fear was that Charles was forfeiting his salvation through his religious disbelief, and this threatened to separate them in death.

Her letter was to go unanswered. "Charles respected Emma's faith and probably kept his religious doubts to himself," van Wyhe says. The man from the English town of Shrewsbury, northwest of Birmingham, had drawn his theories from it. His wife's reactions had shown him how difficult it was to convince other people of his ideas: The criticism would be devastating were he to publish his theories without adequate proof; and his scientific career would be ruined.