February 12 is a landmark date in the history of knowledge - the 200th anniversary of the birth of one of the most important scientists to have ever lived, whose research and writings lay the foundations not only for so much scientific progress since then, but our very understanding of the origins of life.
That man was Charles Darwin, who was educated for a career in the church but whose curiosity as a geologist and naturalist led him to publish the theory of evolution by natural selection. That contradicted the view that had dominated until then - that everything was created by God.
Darwin was not alone at that time in asking and answering such fundamental questions. Alfred Wallace came to similar conclusions and their first pronouncements were made together, to the Linnean Society in 1858.
Darwin lived in an age of nascent secularism, alongside intellectuals such as Thomas Malthus, whose essay on the brutal implications of over-population provided him with key inspiration on the process of natural selection and atheist thinkers such as John Stuart Mill and Karl Marx.
However, it was Darwin's grand opus, On the Origin of Species by Means of Natural Selection, published 150 years ago this year, that provided the detailed evidence and mechanisms for evolution, and was the book that had the most immediate and lasting impact - and that sparked the most controversy.
The double anniversaries are an important opportunity to revisit Darwin's extraordinary life, work and legacy. One reason for this is that the debate that he sparked is far from over.
