Passage 4

Questions 16 to 20 are based on the following passage.

    Historical periods are dominated by distinct sets of ideas which form the general spirit of a period in history. Greek philosophy, Christianity, Renaissance thought, the Scientific Revolution, and the Enlightenment are examples of sets of ideas that dominated their historical periods. The changes from one period to the next are usually rather gradual.; other changes—more abrupt—are often referred to as revolutions. The most far-reaching of all these intellectual changes was the Darwinian revolution. The worldview formed by any thinking person in the Western world after 1859, when On the Origin of Species was published, was by necessity quite different from a worldview formed before 1859. It is almost impossible for a modern person to project back to the early half of the nineteenth century and reconstruct the thinking of this pre-Darwinian period, for the impact of Darwinism on our views has been so great.

    The intellectual revolution brought about by Darwin went far beyond the realm of biology, causing the overthrow of some of the most basic beliefs of his age. For example, Darwin rejected the belief in the individual creation of each species, establishing in its place the concept that all of life descended from a common ancestor. By extension, he introduced the idea that humans were not the special products of creation but evolved according to principles that operate everywhere else in the living world. Darwin upset current notions of a perfectly designed natural and gentle world and substituted in their place the concept of a struggle for survival. Victorian notions of progress and perfectibility were seriously weakened by Darwin's demonstration that evolution brings about change and adaptation, but it does not necessarily lead to progress, and it never leads to perfection.

    Darwin would be remembered as an outstanding scientist even if he had never written a word about evolution. Indeed, some people believe that Darwin’s most original contribution to biology was not the theory of evolution but his series of books on experimental botany published near the end of his life. This achievement is little known among non-biologists, and the same is true for his equally outstanding work on the adaptation of flowers and on animal psychology, as well as his imaginative work on earthworms. Darwin also attacked important problems with extraordinary originality, thereby becoming the founder of several now well-recognized separate disciplines. Darwin was the first person to work out a sound theory of classification, which is still used by most experts today.

 The author considers the change caused by Darwin’s On the Origin of Species ______.