When you inoculate children with a polio vaccine, you don't sleep well for two or three months.

Life is an error-making and an error-correcting process.

There is hope in dreams, imagination, and in the courage of those who wish to make those dreams a reality.

I think of evolution as an error-making and error-correcting process, and we are constantly learning from experience.

My life is pretty well at peace, and the profession is more of an avocation. It's a calling, if you like, rather than a job. I do what I feel impelled to do, as an artist would.

If all the insects were to disappear from the earth, within 50 years all life on earth would end. If all human beings disappeared from the earth, within 50 years all forms of life would flourish.

I feel that the greatest reward for doing is the opportunity to do more.