Jeremy Avigad in Computability and Incompleteness (2002)
... in a sense,computability is similar to the Supreme Court Justice Stewart's characterization of pornography, it may be hard to define precisely, but I know it when I see it."
Not quite from a 'paper' but floating around in the net:
"Who has not been amazed to learn that the function $y = e^xe^x$, like a phoenix rising from its own ashes, is its own derivative?" -- Francois le Lionnais
