Our challenge is to give what account we can of what becomes of life in the solar system, this corner of the universe that is our home; and, most of all, what becomes of men-all men, of all nations, colors, and creeds. This has become one world, a world for all men. It is only such a world that can now offer us life, and the chance to go on.

A scientist is in a sense a learned small boy. There is something of the scientist in every small boy. Others must outgrow it. Scientists can stay that way all their lives.

There are only two possible explanations as to how life arose: Spontaneous generation arising to evolution or a supernatural creative act of God.... There is no other possibility. Spontaneous generation was scientifically disproved 120 years ago by Louis Pasteur and others, but that just leaves us with only one other possibility... that life came as a supernatural act of creation by God, but I can't accept that philosophy because I do not want to believe in God. Therefore I choose to believe in that which I know is scientifically impossible, spontaneous generation leading to evolution.

I tell my students to try early in life to find an unattainable objective.

There is nothing worth having that can he obtained by nuclear war - nothing material or ideological - no tradition that it can defend. It is utterly self-defeating.

Dropping those atomic bombs on Hiroshima and Nagasaki was a war crime.

Since we have had a history, men have pursued an ideal of immortality.