Carl Sagan

"Extraordinary claims require extraordinary evidence."

"There are no forbidden questions in science, no matters too sensitive or delicate to be probed, no sacred truths."

"[When a religious couple wrote to Sagan about fulfilled prophecies, he wrote back in May 1996:]If ‘fulfilled prophecy’ is your criterion, why do you not believe in materialistic science, which has an unparalleled record of fulfilled prophecy? Consider, for example, eclipses."

"We can judge our progress by the courage of our questions and the depth of our answers, our willingness to embrace what is true rather than what feels good."

"Somewhere, something incredible is waiting to be known."

"The way to find out about our place in the universe is by examining the universe and by examining ourselves - without preconceptions, with as unbiased a mind as we can muster."

"A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism."

"We've arranged a civilization in which most crucial elements profoundly depend on science and technology. We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster."

"Somewhere, something incredible is waiting to be known."

"The cosmos is within us. We are made of star-stuff. We are a way for the universe to know itself."

"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."

"La prueba de ausencia no es prueba de ausencia"

"It's a lazy Saturday afternoon, there's a couple lying naked in bed reading Encyclopediea Brittannica to each other, and arguing about whether the Andromeda Galaxy is more 'numinous' than the Ressurection. Do they know how to have a good time, or don't they?"

"The nuclear arms race is like two sworn enemies standing waist deep in gasoline, one with three matches, the other with five."

"The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what's true."

"You could just as well say that an agnostic is a deeply religious person with at least a rudimentary knowledge of human fallibility."

"A new consciousness is developing which sees the earth as a single organism and recognizes that an organism at war with itself is doomed. We are one planet. One of the great revelations of the age of space exploration is the image of the earth finite and lonely, somehow vulnerable, bearing the entire human species through the oceans of space and time."

"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."

"Extraordinary claims require extraordinary evidence."

"If it can be destroyed by the truth, it deserves to be destroyed by the truth."