It is courage based on confidence, not daring, and it is confidence based on experience. - Jonas Salk

There is something about human nature that has to be understood, and so … I've shifted my attention from an interest in unity to an interest in creativity.

Nothing happens quite by chance. It's a question of accretion of information and experience … it's just chance that I happened to be here at this particular time when there was available and at my disposal the great experience of all the investigators who plodded along for a number of years.

We were told in one lecture that it was possible to immunize against diphtheria and tetanus by the use of chemically treated toxins, or toxoids. And the following lecture, we were told that for immunization against a virus disease, you have to experience the infection, and that you could not induce immunity with the so-called "killed" or inactivated, chemically treated virus preparation. Well, somehow, that struck me. What struck me was that both statements couldn't be true. And I asked why this was so, and the answer that was given was in a sense, 'Because.' There was no satisfactory answer.