I have lived much of my life among molecules. They are good company.

I have often had cause to feel that my hands are cleverer than my head. That is a crude way of characterizing the dialectics of experimentation. When it is going well, it is like a quiet conversation with Nature. One asks a question and gets an answer, then one asks the next question and gets the next answer. An experiment is a device to make Nature speak intelligibly. After that, one only has to listen.

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.

[Attributing the origin of life to spontaneous generation.] However improbable we regard this event, it will almost certainly happen at least once.... The time... is of the order of two billion years.... Given so much time, the "impossible" becomes possible, the possible probable, and the probable virtually certain. One only has to wait: time itself performs the miracles.

A scientist should be the happiest of men.

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

There was a golden period that I look back upon with great regret, in which the cheapest of experimental animals were medical students. Graduate students were even better. In the old days, if you offered a graduate student a thiamine-deficient diet, he gladly went on it, for that was the only way he could eat. Science is getting to be more and more difficult.