"The secret of my success is due to my happy facility of being able to draw correct conclusions from imperfect data."

"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

"The world is full of things that are wonderful, but we only see them when we are looking for them."

"It may be a weed instead of a fish that, after all my labour, I at last pull up."

"I have in fact been a very lucky fellow; I have often said that I should be a very miserable creature if I could not feel that I was doing something for the good of other people."