Carl Sagan

"We are the universe made conscious of itself."

"Each discovery opens new questions to investigate."

"The study of nature reveals the handiwork of physical laws."

"We must balance technological advancement with ethical consideration."

"Our curiosity is one of our greatest strengths as a species."

"Science thrives in societies with freedom of thought and expression."

"The cosmos is a vast living body, of which we are still the smallest part."

"For small creatures such as we, the vastness is bearable only through love."

"Science is not only compatible with spirituality; it is a profound source of spirituality."

"All civilizations become either spacefaring or extinct."

"The brain is like a muscle. When it is in use we feel very good about ourselves."

"If you wish to make an apple pie from scratch, you must first invent the universe."

"Understanding is a kind of ecstasy."

"We live in a moment of history where change is so speeded up that we begin to see the present only when it is already disappearing."

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

"The absence of evidence is not the evidence of absence."

"There are many hypotheses in science which are wrong. That is perfectly all right; they're the aperture to finding out what's right."

"One of the saddest lessons of history is this: If we've been bamboozled long enough, we tend to reject any evidence of the bamboozle."

"We make up meanings because we are creatures that crave understanding."

"The fact that life evolved out of nearly nothing, some 5 to 8 billion years after the universe begins suggests life is something precious."

"If we ever detect a signal from an alien civilization, it will almost certainly come from a technology far more advanced than ours."

"Science demands evidence, and in the absence of evidence, it's honest to say we don't know."

"Skeptical thinking is a way of evaluating claims to see what's really true."

"I worry that pseudo-scientific thinking, superstition, and outright nonsense will flourish in the 21st century as never before."

"An atheist is someone who is certain that God does not exist."

"In order to make an apple pie from scratch, you must first understand why there is something rather than nothing."

"The Earth is home. It's the only home we have ever known."

"All life on Earth is made of stardust."

"Books are the means by which we transmit civilization forward in time."

"The beauty of a living thing is not the atoms that go into it, but the way those atoms are put together."