The following is a transcript from the episode One Voice in the Cosmic Fugue from the television series Cosmos: A Personal Voyage (1980)

One Voice in the Cosmic Fugue

All my life, I've wondered about life beyond the Earth. On those countless other planets that we think circle other suns, is there also life? Might the beings of other worlds resemble us, or would they be astonishingly different? What would they be made of? In the vast milky way galaxy, how common is what we call life? The nature of life on Earth, and the quest for life elsewhere, are the two sides of the same question: the search for who we are.

All living things on Earth are made of organic molecules, a complex microscopic architecture built around atoms of carbon. In the great dark between the stars, there also are organic molecules, in immense clouds of gas and dust. And inside such clouds, there are batches of new worlds just forming. Their surfaces are very likely covered with organic molecules. These molecules almost certainly are not made by life, although they are the stuff of life. On suitable worlds, they may lead to life. Organic matter is abundant throughout the Cosmos, produced by the same chemistry everywhere.

Perhaps, given enough time, the origin and evolution of life is inevitable on every clement world. There will surely be some planets too hostile for life. On others, it may arise and die out or never evolve beyond its simplest forms. And on some small fraction of worlds, there may develop intelligences and civilizations more advanced than ours.

All life on our planet is closely related. We have a common organic chemistry and a common evolutionary heritage, and so our biologists are profoundly limited; they study a single biology – one lonely theme in the music of life. Is it the only voice for thousands of light years? Or is there a cosmic fugue? – a billion different voices playing the life music of the galaxy.