Carl Sagan

"We make up meanings because we can and we need to. It is how we create purpose."

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

"Extraordinary claims require extraordinary evidence, but the burden of proof is always on the claimant."

"We should always be suspicious of those who claim to have the truth, and skeptical of those who claim certainty."

"The dangers of nuclear war are almost incomprehensible. Yet we still play with fire."

"To make an apple pie from scratch, you must first invent the universe."

"Imagination will often carry us to worlds that never were. But without it we go nowhere."

"What an astonishing thing a book is. It's a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles."

"The fact that life evolved out of nearly nothing, some 4 billion years after the universe began, is a lesson in how precious each and every one of us is."

"When you're in love, you want to tell the world."

"We are made of the stuff of stars. We are a way for the universe to examine itself."

"The greatest gift we can give is critical thinking and the courage to use it."

"As science advances, it does not prove that God does not exist. Rather, it opens up new mysteries."

"Money is a powerful motivator, but it is not the ultimate measure of success."

"We have a responsibility to be good stewards of the cosmos."

"The universe is a pretty big place. We should be humble about our place in it."

"If you want to make an apple pie, you need not only the apples but also the knowledge of how to bake."

"Science is a method for testing claims against the universe, not a religion or philosophy."

"One thing I notice is that the more we know about the world, the less arrogant we can be."

"The truth may be puzzling. It may contradict deeply held beliefs. But we must follow it wherever it leads."

"What a profound and moving fact it is that we are alive. We should never stop being amazed by it."

"History teaches us that in periods of freedom, people tend to accumulate power and knowledge."

"We are children of the stars. Literally. We came from them."

"If I am skeptical, it is because I respect the universe too much to accept easy answers."

"The universe will not allow you to live in comfortable delusions."

"Science and reason have brought us so far. We must not abandon them now."

"To protect the environment is to protect ourselves and our future."

"The greatest joy is in understanding. Everything else is secondary."

"We inherit the work of countless generations before us. We have a duty to those who come after."

"A single human being is a magnificent achievement of cosmic construction."