Is evolution true? If so, what is the force that drives it? Can natural selection account for so complex an organ as the eye--or is Darwin's theory merely what an eminent nineteenth-century astronomer call 'the law of higgledy-piggledy'? Is molecular evolution a random process? What is the real relationship between the theory of evolution and biological classification? Why do living things appear to come to recognizable units called species, and how can one species split into two? Does evolution proceed gradually, or in jerks? What causes the grand patterns of change in the fossil record?