Fire grows and spreads because it creates the conditions to do so by itself. A small local fire turns up the temperature and drives away moisture in its immediate surroundings, creating the conditions for combustion. Once its immediate surroundings are lit on fire, the conditions are created in the layer surrounding that, and so on. In this way, a spark, an ember blown by the wind, a cigarette tossed carelessly out of a car, can start a vast and uncontrollable conflagration. Most living beings in the forest are burned to death, and the few that escape can never return, because the very conditions for life have been destroyed.