The measures taken during the war by our military agencies, in restricting the free intercourse among scientists on related projects or even on the same project have gone so far that it is clear that if continued in time of peace, this policy will lead to the total irresponsibility of the scientist, and, ultimately, to the death of science. ...The interchange of ideas, which is one of the greatest traditions of science, must of course receive certain limitations when the scientist becomes an arbiter of life and death. ...