Will humans be able to utilize their brains to save themselves from extinction? This is the central question, Hannes Alfvén addresses in this lecture, and his answer is pessimistic: Prospects aren’t good. We are rushing towards an era that will be characterized by real nuclear wars rather than by nuclear threats only. The Cold War was - despite of a climate of thawing - still the major background of world politics and the arms race between the two super powers was ongoing at an accelerating pace, when Alfvén held this lecture. He was both concerned and committed. From 1970 to 1975 he had served as the president of the Pugwash Conferences on Science and World Affairs, which had been founded in 1957 with the intention to eliminate all weapons of mass destruction. In 1971, the year after he had received the Nobel Prize for fundamental discoveries in astrophysics, he had spoken about his work for the Pugwash conferences in Lindau for the first time. In 1976 he focused on the responsibility of scientists to reduce the threat of a nuclear war. The intensity of his thoughts seems to be amplified by his specific intonation of the German language, both sharp and soft, determined and dreamy. It was the only time that Alfvén lectured in German in Lindau, the polyglot Swedish humanist who was in fluent command of five languages. If an “omnicide” is potentially imminent, shouldn’t then mainly scientists be responsible to research and develop appropriate countermeasures? By their discovery of nuclear fission, they have brought humankind into this dangerous situation, after all. As a united global think tank they would certainly be capable to find out what to do. Yet about 400,000 scientists worldwide, Alfvén says, are employed in military research. Their work is dedicated to invent new weapons. They are part of the military-industrial complex. This complex is not so much a result of a conspiracy of leaders but rather a result of the inclination of most people, including scientists, to be loyal employees. Slowing down the arms race could endanger their jobs. Not more than a few hundred scientists worldwide would be willing to discuss the consequences of their work. To understand the mechanisms behind the arms race, Alfvén recommends to read Herbert Yorks book “The race to oblivion”. From an US participant’s view it uncovered a paradox: Each single US-decision to build up arms is rationally justified – yet the sum of these decisions resulted in a continuos decline of national security because each of them triggered respective Soviet reactions. The future of the divided Europe, whose fate he sees lying in the hands of the superpowers is a special concern of Alvén. While at least 10,000 nuclear warheads were based in or directed towards Europe, he says, there’d be amazingly little public discussion about this threat. From today’s perspective, Alfvén seems to exaggerate. In his time, however, his analysis hit the mark. It gives a realistic flavor of a historical period, whose real fears culminated in the peace movement of the early eighties. And with regard to the responsibility of scientists, many of Alfvén’s remarks remain timeless.