More quotes by Carl Sagan

"Extraordinary claims require extraordinary evidence."
"Science is based on experiment, on a willingness to challenge old dogma, on an openness to see the universe as it really is. Accordingly, science sometimes requires courage - at the very least the courage to question the conventional wisdom."
"I consider it an extremely dangerous doctrine, because the more likely we are to assume that the solution comes from the outside, the less likely we are to solve our problems ourselves."
"Somewhere, something incredible is waiting to be known."