" What happens when an animal or person dies? Something seems to have departed--something like a vital spark that makes the difference between life and death. In the nineteenth century, philosophers believed that there really was such a thing and called it the élan vital, or vital spirit. But when twentieth century science began to unravel the mysteries of how living things work and reproduce, the idea was abandoned and people now accept that there is nothing more to being alive than complex, interrelated, biological functions. "

― Susan Blackmore , Conversations on Consciousness: What the Best Minds Think about the Brain, Free Will, and What It Means to Be Human