"Religion was not an issue in my family; indeed, it was never discussed. My only religious training came because the Minta required that all students take classes in their respective religions. My family celebrated one holiday, the Day of Atonement, when we all fasted. Yet my father said prayers for his parents on Saturdays and on all the Jewish holidays. The idea of God that I absorbed was that it would be wonderful if He existed: We needed Him desperately but had not seen Him in many thousands of years."

"I contributed; Ulam did not. I'm sorry I had to answer it in this abrupt way. Ulam was rightly dissatisfied with an old approach. He came to me with a part of an idea which I already had worked out and difficulty getting people to listen to. He was willing to sign a paper. When it then came to defending that paper and really putting work into it, he refused. He said, "I don't believe in it.""

"My name is not Strangelove. I don't know about Strangelove. I'm not interested in Strangelove. What else can I say?... Look. Say it three times more, and I throw you out of this office."

"I think it is a sad reflection on our civilisation that while we can and do measure the temperature in the atmosphere of Venus, we do not know what goes on inside our souffles."

"A great power imposes the obligation of exercising restraint, and we did not live up to this obligation. I think this affected many of the scientists in a subtle sense, and it diminished their desire to continue to work on the bomb."

"After the war ended, partly disgusted by the cruel use to which his beloved physics had been put, Szilard left professional physics to explore new pastures – in his case, biology... there was a more pragmatic reason. As Szilard put it, this was an age when you took a year to discover something new in physics but only took a day to discover something new in biology."

"By the time his ideas became accepted he had already forged ahead to take up a new attitude. Szilard himself illustrated this characteristic in a story which he liked to tell about himself. He served once on a jury in a murder case. When the first vote was taken, eleven jurors were in favour of convicting, but one — Szilard — was for acquittal. Since unanimity was required, the discussion was resumed and Szilard expounded his arguments. After some time another vote was taken; the result was again eleven to one, but this time eleven were for acquittal, and one for conviction: the odd vote was Szilard’s who had in the meantime changed his mind!"

"I had not been long back from Hiroshima when I heard someone say, in Szilárd's presence; that it was the tragedy of scientists that their discoveries were used for destruction. Szilárd replied, as he more than anyone else had the right to reply; that it was not the tragedy of scientists, it is the tragedy of mankind."

"The people who have sufficient passion for the truth to give the truth a chance to prevail, if it runs counter to their bias, are in a minority. How important is this "minority?" It is difficult to say at this point, for, at the present time their influence on governmental decisions is not perceptible."

"Even in times of war, you can see current events in their historical perspective, provided that your passion for the truth prevails over your bias in favor of your own nation."

"I sometimes have the feeling that I have lived through all this before and, in a sense, I have. I was sixteen years old when the first World War broke out, and I lived at that time in Hungary. From reading the newspapers in Hungary, it would have appeared that, whatever Austria and Germany did was right and whatever England, France, Russia, or America did was wrong. A good case could be made out for this general thesis, in almost every single instance. It would have been difficult for me to prove, in any single instance, that the newspapers were wrong, but somehow, it seemed to me unlikely that the two nations located in the center of Europe should be invariably right, and that all the other nations should be invariably wrong. History, I reasoned, would hardly operate in such a peculiar fashion, and it didn't take long until I began to hold views which were diametrically opposed to those held by the majority of my schoolmates."

"Even if we accept, as the basic tenet of true democracy, that one moron is equal to one genius, is it necessary to go a further step and hold that two morons are better than one genius?"

"Suppose Germany had developed two bombs before we had any bombs. And suppose Germany had dropped one bomb, say, on Rochester and the other on Buffalo, and then having run out of bombs she would have lost the war. Can anyone doubt that we would then have defined the dropping of atomic bombs on cities as a war crime, and that we would have sentenced the Germans who were guilty of this crime to death at Nuremberg and hanged them? But, again, don't misunderstand me. The only conclusion we can draw is that governments acting in a crisis are guided by questions of expediency, and moral considerations are given very little weight, and that America is no different from any other nation in this respect."

"A man's clarity of judgment is never very good when you're involved, and as you grow older, and as you grow more involved, your clarity of judgment suffers."

"All we had to do was lean back, turn a switch and watch a screen of a television tube. If flashes of light appeared on the screen it would mean that liberation of atomic energy would take place in our lifetime. We turned the switch, saw the flashes — we watched for about five minutes — then switched everything off and went home. That night I knew the world was headed for trouble."

"Science is progressing at such a rapid rate that when you make a prediction and think you are ahead of your time by 100 years you may be ahead of your time by 10 at most."

"In life you must often choose between getting a job done or getting credit for it. In science, the most important thing is not the ideas you have but the decision which ones you choose to pursue. If you have an idea and are not doing anything with it, why spoil someone else's fun by publishing it?"

"It is not necessary to succeed in order to persevere. As long as there is a margin of hope, however narrow, we have no choice but to base all our actions on that margin. America and Russia have one interest in common which may override all their other interests: to be able to live with the bomb without getting into an all-out war that neither of them wants."

"In order to succeed it is not necessary to be much cleverer than other people. All you have to do is be one day ahead of them."

"The most important step in getting a job done is the recognition of the problem. Once I recognize a problem I usually can think of someone who can work it out better than I could."

"A scientist's aim in a discussion with his colleagues is not to persuade, but to clarify."

"I'm looking for a market for wisdom."

"Another explanation for the failure of logic and observation alone to advance medicine is that unlike, say, politics, which uses a form of logic – mathematics – as its natural language, biology does not lend itself to logic. Leo Szilard, a prominent physicist, made this point when he complained that after switching from physics to biology he never had a peaceful bath again. As a physicist he would soak in the warmth of the bathtub and contemplate a problem, turn it in his mind, reason his way through it. But once he became a biologist, he constantly had to climb out of the bathtub to look up a fact."

"If we focus our attention on the next twenty-five years we may say that development is likely to reach some point intermediate between the first bomb detonated over Hiroshima and processes which once initiated might put an end to all life on earth. Just what intermediate point will be reached within twenty-five years no one can tell."