All this was well enough in the days of naïvely vitalistic ideas of the world as having a life and soul. But not in these days of mechanics, the strict calculation of the amount of energy used, and the mechanical theory of heat. The world-clock cannot wind itself up. It, too, owes its activity to the transformation of potential energy into kinetic energy. And, since movement and work take place within it, there is in the clock as a whole just as in every one of its parts, a mighty process of relaxation of an originally tense spring, there is dissipation and transformation of the stored potential energy into work and ultimately into heat. And with every revolution of the earth and its moon the world is moving slowly but inexorably towards a final stage of complete relaxation of her powers of tension, a state in which all energy will be transformed into heat, in which there will be no different states but only the most uniform distribution, in which also all life and all movement will cease and the world-clock itself will come to a standstill. How does this fit in with the idea of independence and self-sufficiency? How could the world-clock ever wind itself up again to the original state of tension which was simply there as if shot from a pistol “in the beginning”? Where is the everlasting impressive uniformity and constancy of the world? How does it happen that the world-clock has not long ago come to a standstill? For even if the original sum of potential energy is postulated as infinite, the eternity that lies behind us is also infinite. And so one infinity swallows another. And innumerable questions of a similar kind are continually presenting themselves. The “Contingency” of the World.