Major theorists from the 17th and 18th centuries include Isaac Newton, whose laws of motion and illumination of gravity have been seen as a keystone of modern science; from the 19th century Charles Darwin, whose theory of evolution by natural selection was fundamental to the development of modern biology, and James Clerk Maxwell, who formulated classical electromagnetic theory; and more recently Stephen Hawking, who has advanced major theories in the fields of cosmology, quantum gravity and the investigation of black holes.