Clergymen almost necessarily fail in two ways as teachers of morals. They condemn acts which do no harm and they condone acts which do great harm.

If everything must have a cause, then God must have a cause. If there can be anything without a cause, it may just as well be the world as God, so that there cannot be any validity in that argument... The idea that things must have a beginning is really due to the poverty of our imagination.

It is a natural propensity to attribute misfortune to someone's malignity.

Suppose atomic bombs had reduced the population of the world to one brother and sister; should they let the human race die out?

I would never die for my beliefs because I might be wrong.

The most savage controversies are about matters as to which there is no good evidence either way.

The human race may well become extinct before the end of the century.