Reply when questioned on the safety of the polio vaccine he developed: It is safe, and you can't get safer than safe.
When you inoculate children with a polio vaccine, you don't sleep well for two or three months.
When I worked on the polio vaccine, I had a theory. I guided each [experiment] by imagining myself in the phenomenon in which I was interested. The intuitive realm . . . the realm of the imagination guides my thinking.