Science is a wonderful thing if one does not have to earn one's living at it.
We don't have the money, so we have to think.
I found both these quotes in Barbara Goldsmith's excellent biography of Marie Curie: Obsessive Genius: The Inner World of Marie Curie. [You can read the reviews of this book in the Guardian, and the American Scientist.] I plan post some excerpts from this book in the next day or two.