Breathing has become so mundane that we hardly ever notice it, but if we stop and consider what’s happening every moment of our lives, it almost takes our breath away. Every few moments we inhale a complex mixture of nitrogen, oxygen, argon and carbon dioxide, and our lungs expand and our capillaries absorb the oxygen. It races through our bloodstream, pumped to all corners of our bodies by a lump of muscle and tissue that knocks against our rib cages and never gets an answer, but keeps on supporting us for our whole lifetimes anyway, for 2.5 billion beats in the complex song of life. We are intricate systems of muscles, nerves and tissue, wound together on a frame of hardened collagen and calcium, like the coral upon which a reef ecoystem depends. We are the products of four billion years of evolution, owing our every atom to the seething furnaces of a long-gone stellar explosions. We are machines, all of us: organic machines made of flesh and blood and sinew and a billion electrical impulses that pay tribute to our celestial ancestry, lighting up our brains like the stars light up the darkness. We are such fragile, soft machines.