The human capacity for guilt is such that people can always find ways to blame themselves

I think those who have a terminal illness and are in great pain should have the right to choose to end their own life, and those that help them should be free from prosecution.

We are very, very small, but we are profoundly capable of very, very big things.

Do you ever wonder how much deeper the ocean would be without sponges?

Keeping an active mind has been vital to my survival, as has been maintaining a sense of humor.

I think the next [21st] century will be the century of complexity. We have already discovered the basic laws that govern matter and understand all the normal situations. We don't know how the laws fit together, and what happens under extreme conditions. But I expect we will find a complete unified theory sometime this century. The is no limit to the complexity that we can build using those basic laws.

It was recently discovered that research causes cancer in rats.