A man that is of Copernicus’ Opinion, that this Earth of ours is a Planet, carry’d round and enlightn’d by the Sun, like the rest of them, cannot but sometimes have a fancy … that...

Life is not a miracle. It is a natural phenomenon, and can be expected to appear whenever there is a planet whose conditions duplicate those of the earth.[Stating how planets supporting life cannot be rare.]

[My study of the universe] leaves little doubt that life has occurred on other planets. I doubt if the human race is the most intelligent form of life.

Do there exist many worlds, or is there but a single world? This is one of the most noble and exalted questions in the study of Nature.

However life started, once established, it persisted for over 3.5 billion years and evolved from microbial slime to the sophistication of human civilization.