Nigel Warburton: What is energy?
Caspar Henderson: Energy is eternal delight, according to William Blake! Or to take another view, as a living system we are obviously subject to the second law of thermodynamics, among other things. According to the biochemist Albert Szent-Györgyi, life is an electron looking for a place to rest. We need to have a flow of energy to sustain life, to sustain metabolism.
And that’s primarily in terms of water, food, making a shelter, and generating some heat ...