It seems like a simple question: what makes something alive? We know it when we see it – a bird in flight, a growing tree, a scurrying insect. Yet, as Don Simborg reveals here, the scientific community has been locked in a millennia-long struggle to find a definition that actually sticks. From the earliest philosophical musings to the complexities of "Vitalism" and the pioneering insights of Erwin Schrödinger, this book explores why every attempt to define life seems to hit a wall. Moving beyond simple lists of plants and animals, this engaging quest dives into the functional essence of existence. Simborg examines the modern candidates for the "essence of life” – from the presence of DNA and cellular membranes to the "Seven Pillars of Life". Is it metabolism, evolution or the ability to die that defines us? By dissecting the flaws in our current scientific language and exploring the "facts of life" that complicate our understanding, What is Life? challenges readers to rethink their place in the universe. It is a must-read for anyone curious about the fundamental mystery that separates a collection of chemicals from a living, evolving being.