In ancient times, life was typically viewed as a principle or essence: qi in China, ase in Nigeria, mana in Polynesia, manitou in the Algonkian cultures of North America, pneuma to the Greeks, the Force in a galaxy far, far away. Living creatures and non-living things are both made of matter, long-ago thinkers said. But the former eat, reproduce, act with intent, and do a hundred other things that seem beyond the capacities of the non-living. It was easy for the ancients to explain the gulf between life and non-life by imagining that a special kind of immaterial energy flows through and
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