Carl Sagan

The universe seems neither benign nor hostile, merely indifferent to the concerns of such puny creatures as we are.

They (i. e., the Pythagoreans) did not advocate the free confrontation of conflicting points of view. Instead, like all orthodox religions, they practised a rigidity that prevented them from correcting their errors.

War is murder writ large.

The Hindu religion is the only one of the world’s great faiths dedicated to the idea that the cosmos itself undergoes an immense and indeed an infinite number of deaths and rebirths. It is the only religion in which the time scales correspond […] to those of modern scientific cosmology.

If we like them, they're freedom fighters, she thought. If we don't like them, they're terrorists. In the unlikely case we can't make up our minds, they're temporarily only guerrillas.

If a marker were to be erected today, it might read, in homage to his scientific courage: “He preferred the hard truth to his dearest illusions.”

The Platonists and their Christian successors held the peculiar notion that the Earth was tainted and somehow nasty, while the heavens were perfect and divine. The fundamental idea that the Earth is a planet, that we are citizens of the Universe, was rejected and forgotten.

A googolplex is precisely as far from infinity as is the number 1... no matter what number you have in mind, infinity is larger still.

Relativity does set limits on what humans can ultimately do. But the universe is not required to be in perfect harmony with human aspirations.

Our intelligence and our technology have given us the power to affect the climate. How will we use this power? Are we willing to tolerate ignorance and complacency in matters that affect the entire human family? Do we value short-term advantages above the welfare of the Earth? Or will we think on longer time scales, with concern for our children and our grandchildren, to understand and protect the complex life-support systems of our planet? The Earth is a tiny and fragile world. It needs to be cherished.

Matter is composed chiefly of nothing.

In the vastness of space and the immensity of time, it is my joy to share a planet and an epoch with Annie.