Darwin’s thinking about evolution was not only deep, but also very broad. He was interested in fossils, animal breeding, geographical distribution, anatomy and plants. “That very comprehensive view allowed him to see things that others perhaps didn’t,” says Robert J. Richards, a historian at the University of Chicago. “He was so sure of his central ideas — the transmutation of species and natural selection — that he had to find a way to make it all work together.” (Dr. Richards comments on "On the Origin of Species.")

From the perspective of 2009, Darwin’s principal ideas are substantially correct. He did not get everything right. Because he didn’t know about plate tectonics, Darwin’s comments on the distribution of species are not very useful. His theory of inheritance, since he had no knowledge of genes or DNA, is beside the point. But his central concepts of natural selection and sexual selection were correct. He also presented a form of group-level selection that was long dismissed but now has leading advocates like the biologists E. O. Wilson and David Sloan Wilson.

Not only was Darwin correct on the central premises of his theory, but in several other still open issues his views also seem quite likely to prevail. His idea of how new species form was long eclipsed by Ernst Mayr’s view that a reproductive barrier like a mountain forces a species to split. But a number of biologists are now returning to Darwin’s idea that speciation occurs most often through competition in open spaces, Dr. Richards says.

Darwin believed there was a continuity between humans and other species, which led him to think of human morality as related to the sympathy seen among social animals. This long-disdained idea was resurrected only recently by researchers like the primatologist Frans de Waal. Darwin “never felt that morality was our own invention, but was a product of evolution, a position we are now seeing grow in popularity under the influence of what we know about animal behavior,” Dr. de Waal says. “In fact, we’ve now returned to the original Darwinian position.”

It is somewhat remarkable that a man who died in 1882 should still be influencing discussion among biologists. It is perhaps equally strange that so many biologists failed for so many decades to accept ideas that Darwin expressed in clear and beautiful English.