Walt Disney
I've had this quote up on my wall since the very beginning.
"We don't make movies to make money, we make money to make more movies."
-- Walt Disney
I think it probably also rings true for many scientists.
We ran a department in Seed for a couple of years called "Why I Do Science" edited by Josh Roebke and Lee Billings with personal essays written by scientists (one of my favorite departments). Here's one by Brazilian neuroscientist Sidarta Ribeiro. I'll find some more and post them.
Why do you do science?