When we pursue knowledge about the origin of life, we’re thinking about what life is. Is life self-replicating information? Is life a new way for the universe to organize energy? Is it, as Carl Sagan and others have put it, a way for the universe to experience—and hope to understand—itself?

“Definitions tell us about the meanings of words in our language, as opposed to telling us about the nature of the world.” She says that what we need is not a definition but a theory, to know not what the word life means to us, but what life is. But with neither a theory nor a definition, we’re left with our intuition, entirely shaped by the life w

Try as we might to imagine alien animals, what we’re really doing is finding another way to understand life here on Earth.

He offers two lights to guide us: the warm light of community and “the cold light of the stars,” as from that cosmic perspective—that which the whole book has been written to offer—our struggle seems not less meaningful but, somehow, more. Stapledon illustrates a path and prescription, a vision of advancement that values creativity, communication,

Walker thinks that our understanding of life, as a phenomenon, is right now where we were with gravity before Newton. We can describe what we see, but we have no sense of the underlying principles—we just see an apple falling to the ground. She thinks that without a theory, a deeper understanding of what life is, the search for it beyond Earth is p

The anthropologist and nature writer Loren Eiseley writes, “There is nothing more alone in the universe than man.” Surrounded by animals, he says, we humans find ourselves separated from our natural kin by self-awareness, by language, by history.

“Life is a copiously branching bush,” Gould writes, “continually pruned by the grim reaper of extinction, not a ladder of predictable progress.”

That, Losos said, leads to the idea of an entire way of life without species. What if there were no hard boundaries between one animal and another, just “a smear of variation”?

“There is a fear of the night that is begotten of ignorance and superstition, a nightmare fear, the fear of the impossible; and there is another fear of the night—of the starlit night—that comes with knowledge, when we see in its true proportion this little life of ours...”