●Although scientists and philosophers dating back to the Greek civilization had suggested that species 'evolved' rather than remaining fixed, Darwin's Origin of Species (published in 1859) challenged contemporary thought and belief in Divine Providence. ●In its clarification of the hypothesis of the survival of the fittest - that is the protection of certain well-adapted species by their environment - Darwin set down theories of natural selection and explained why certain species become extinct while others flourish. Without setting out to be controversial, Darwin nevertheless upturned the view that the Universe was ordered by a benevolent God. Instead he depicted a world where existence depended on chance and struggle. As such, he was possibly the most revolutionary writer of the Victorian age and this, his greatest work, is considered a landmark in scientific and philosophical thought.