all men because the sun makes it grow and there is much solar heat stored away in it. Grain warms whoever eats it.
Fuel and lumber are useful because there is much heat in them. Whoever buys fuel for winter's use, buys solar heat. And in winter you can burn your fuel whenever you please and liberate the solar heat into your room.
And when there is heat there is also motion. Whatever motion there is, it all comes from heat either directly from the sun's heat or from heat stored away by the sun in coal, in firewood, in grain, and in grass. Horses and cattle draw loads, men work; what moves them? Heat. But whence comes the heat? From food. But the food was produced by the sun.
Water-mills and windmills are set in motion and grind. What moves them? Wind and water. But what drives the wind? Heat. And what drives the water? Heat, to be sure. It raises the water in the form of vapor into the sky, and if it were not for heat the water would not fall.
A machine does work. Steam moves it. What makes the steam? Fuel; and in the fuel is the sun's heat.
Out of heat comes motion, and out of motion comes heat. And both the heat and the motion are due to the sun.
