When I wake up I go through an abbreviated process of mourning all over again. Plainly, there’s something within me that’s ready to believe in life after death. And it’s not the least bit interested in whether there’s any sober evidence for it.

— Carl Sagan

When we look up at night and view the stars, everything we see is shinning because of distant nuclear fusion.

— Carl Sagan

When you look more generally at life on Earth, you find that it is all the same kind of life. There are not many different kinds; there's only one kind. It uses about fifty fundamental biological building blocks, organic molecules.

— Carl Sagan

While ritual, emotion and reasoning are all significant aspects of human nature, the most nearly unique human characteristic is the ability to associate abstractly and to reason. Curiosity and the urge to solve problems are the emotional hallmarks of our species; and the most characteristically human activities are mathematics, science, technology, music and the arts--a somewhat broader range of subjects than is usually included under the "humanities." Indeed, in its common usage this very word seems to reflect a peculiar narrowness of vision about what is human. Mathematics is as much a "humanity" as poetry.

— Carl Sagan

Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people.

— Carl Sagan

Who is humbler? The scientist who looks at the universe with an open mind and accepts whatever the universe has to teach us, or somebody who says everything in this book must be considered the literal truth and never mind the fallibility of all the human beings involved?

— Carl Sagan

Why are there no nonhuman primates with an existing complex gestural language? One possible answer, it seems to me, is that humans have systematically exterminated those other primates who displayed signs of intelligence.

— Carl Sagan

Why do we put up with it? Do we like to be criticized? No, no scientist enjoys it. Every scientist feels a proprietary affection for his or her ideas and findings. Even so, you don’t reply to critics, Wait a minute; this is a perfect idea; I’m very fond of it; it’s done you no harm; please leave it alone. Instead, the hard but just rule is that if the ideas don’t work, you must throw them away.

— Carl Sagan

Why is the half of humanity with a special sensitivity to the preciousness of life, the half untainted by testosterone poisoning, almost wholly unrepresented in defense establishments and peace negotiations worldwide? [blurb on Daniella Gioseffi's _Women on War_; quoted in Carol Lynn Pearson's _The Ghost of Eternal Polygamy_]

— Carl Sagan

With rare exceptions (chiefly the social insects), mammals and birds are the only organisms to devote substantial attention to the care of their young; an evolutionary development that, through the long period of plasticity which it permits, takes advantage of the large information-processing capability of the mammalian and primate brains. Love seems to be an invention of the mammals.

— Carl Sagan