Carl Sagan, words from Cosmos: A Personal Voyage (1980), principally episode 12, "Encyclopaedia Galactica":
The ash of stellar alchemy had emerged into consciousness.
We are a way for the cosmos to know itself.
We are star stuff harvesting starlight.
We humans long to be connected with our origins, so we create rituals. Science is another way to express this longing. It also connects us with our origins, and it too has its rituals and its commandments. Its only sacred truth is that there are no sacred truths. All assumptions must be critically examined. Arguments from authority are worthless. Whatever is inconsistent with the facts, no matter how fond of it we are, must be discarded or revised. Science is not perfect, it’s often misused, it’s only a tool, but it’s the best tool we have: self-correcting, ever-changing, applicable to everything. With this tool, we vanquish the impossible. With the methods of science we have begun to explore the cosmos.
We have learned to value careful observations, to respect the facts even when they are disquieting, when they seem to contradict conventional wisdom.
The Canterbury monks faithfully recorded an impact on the moon and the Anasazi people, an explosion of a distant star.
They saw for us as we see for them.
We see further than they only because we stand on their shoulders.
We build on what they knew.
We depend on free inquiry and free access to knowledge.
We humans have seen the atoms which constitute all of matter and the forces that sculpt this world and others.
We know the molecules of life are easily formed under conditions common throughout the cosmos.
We have mapped the molecular machines at the heart of life.
We have discovered a microcosm in a drop of water.
We have peered into the bloodstream and down on our stormy planet to see the Earth as a single organism.
We have found volcanoes on other worlds and explosions on the sun, studied comets from the depths of space and traced their origins and destinies, listened to pulsars and searched for other civilizations.
We humans have set foot on another world in a place called the Sea of Tranquility, an astonishing achievement for creatures such as we whose earliest footsteps are preserved in the volcanic ash of East Africa.
We have walked far.
These are some of the things that hydrogen atoms do given 15 billion years of cosmic evolution.
It has the sound of epic myth.
But it's simply a description of the evolution of the cosmos as revealed by science in our time.
And we—we who embody the local eyes and ears and thoughts and feelings of the cosmos—we've begun, at last, to wonder about our origins.
Star stuff, contemplating the stars, organized collections of 10 billion-billion-billion atoms contemplating the evolution of matter, tracing that long path by which it arrived at consciousness here on the planet Earth and perhaps throughout the cosmos.
Our loyalties are to the species and the planet.
We speak for Earth.
Our obligation to survive and flourish is owed not just to ourselves but also to that cosmos, ancient and vast from which we spring.