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.

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

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

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.

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

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.

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.