J. D. Bernal was a scientist who helped to pioneer the use of x-ray crystallography and was a founder of the science of molecular biology. He was also well-known as a communist and closely associated with the peace movement. Originally published in 1958, revised in 1961, this title was written, in the author's words, to bring together the dark and the bright side of the new power that science has given to the mankind. At a time when politics was dominated by the hydrogen bomb and the rocket. People, for the first time in their history, were having to contemplate the potential destruction of civilization and even of life itself. While at the same time aware of the benefits of the opening stages of a new industrial revolution.