Charles Darwin: "I love fools' experiments. I am always making them." (http://www.darwin-literature.com/l_quotes.html)
"The very essence of instinct is that it's followed independently of reason." (http://www.brainyquote.com/quotes/authors/c/charles_darwin.html)
Florence Nightingale: "How very little can be done under the spirit of fear." (http://thinkexist.com/quotes/florence_nightingale/)
"Were there none who were discontented with what they have, the world would never reach anything better." (http://thinkexist.com/quotes/florence_nightingale/)
Stephen Hawking: "I have noticed even people who claim everything is predestined, and that we can do nothing to change it, look before they cross the road." (http://www.brainyquote.com/quotes/authors/c/stephen_hawking.html)
"It matters if you just don't give up." (http://www.saidwhat.co.uk/quotes/famous/stephen_hawking)