Intellectual freedom is the only guarantee of a scientific - democratic approach to politics, economic development, and culture.

I could not stop something I knew was wrong and terrible. I had an awful sense of powerlessness.

I regard the death penalty as a savage and immoral institution that undermines the moral and legal foundations of society.

Both now and for always, I intend to hold fast to my belief in the hidden strength of the human spirit.

International affairs must be completely permeated with scientific methodology and a democratic spirit, with a fearless weighing of all facts, views, and theories, with maximum publicity of ultimate and intermediate goals, and with a consistency of principles.

I've always thought that the most powerful weapon in the world was the bomb and that's why I gave it to my people, but I've come to the conclusion that the most powerful weapon in the world is not the bomb but it's the truth

Do not trust governments more than governments trust their own people.

My present work concerns the problems connected with the theory of elementary particles, the theory of gravitation and cosmology and I shall be glad if I can manage to make some contribution to these important branches of science.

You can't sit on two chairs at once.

Our country, like every modern state, needs profound democratic reforms. It needs political and ideological pluralism, a mixed economy and protection of human rights and the opening up of society.

In 1947 I defended my thesis on nuclear physics, and in 1948 I was included in a group of research scientists whose task was to develop nuclear weapons.

I regard the death penalty as a savage and immoral institution that undermines the moral and legal foundations of society. I reject the notion that the death penalty has any essential deterrent effect on potential offenders. I am convinced that the contrary is true - that savagery begets only savagery.

Profound insights arise only in debate, with a possibility of counterargument, only when there is a possibility of expressing not only correct ideas but also dubious ideas.

A country which does not respect the rights of its own citizens will not respect the rights of its neighbours

For me, the moral difficulties lie in the continual pressure brought to bear on my friends and immediate family, pressure which is not directed against me personally but which at the same time is all around me.

In and after 1964 when I began to concern myself with the biological issues, and particularly from 1967 onwards, the extent of the problems over which I felt uneasy increased to such a point that in 1968 I felt a compelling urge to make my views public.