So Heat, dancing down the rays of the Sun, turned the water at the surface of the Ocean into vapour, like steam, and it rose high in the air and formed clouds. Then Wind drove the clouds over the valley, and Cold blew on them, and turned the vapour of the clouds back to water again, so that it fell as Rain. Now each little bit of vapour in the clouds carried with it a tiny spark of Electricity, for the Air about the Earth is always filled with Electricity, carried by tiny drops of moisture. When all the little sparks got together in the thick black clouds, they formed big sparks, and when the clouds got so full of Electricity they couldn't hold any more, these big sparks jumped from the clouds down to the Earth, in great flashes, sometimes half a mile long. You can make a little spark like that, if you walk quickly over a soft rug, on a dry winter day, and then put your knuckle to the metal radiator. It will be a real Lightning flash, although it will be only half an inch long, and the little crackling sound you hear, as the spark jumps from your knuckle to the radiator, is real thunder, but because the flash is so small, your thunder will not be very loud.
So the storm rolled down over the valley, and the Lightning flashed, and the Thunder roared, and all the cave people ran into their holes and huddled together, shivering. They had seen the Lightning and heard the Thunder before, but because they did not know what they were, they thought some terrible dragon, with a roaring voice and a tongue of flame was coming to eat them up.
At last a great flash of Lightning struck a dry tree and set it on fire, and the Wind blew the clouds away for a while, so that the Rain might not put the fire out.
"I'll show them something," said Heat, as the tree and the bushes about it began to crackle and blaze.
As soon as Wind blew the storm away, the cave people, not hearing the Thunder any more, came out to see what was going on. When they saw the blazing tree, they were at first very much frightened, for they had never seen Fire so close at hand before. So they chattered and pointed, afraid to go near it.
After a while, when they saw that the fire did them no harm, they went closer, and gathered about the roaring flames, watching them as they devoured the dry leaves and branches.
Then Mother Nature told Wind to blow the flames gently toward the cave people, and the heat from the flames warmed them, and they liked it. So they came nearer, and at last a boy picked up a blazing branch that fell near him, because it was red and pretty. But he dropped it again very quickly, you may be sure, and ran howling with pain to his mother, his burnt fingers in his mouth.
"I am sorry," laughed Heat, dancing among the flames, "but I had to let you see that I can burn as well as warm you. So you had better treat me with care."
Soon the flames spread, and other trees took fire, and the flames roared and danced down the valley like mad, their red tongues licking up everything that came in their way.
Some of the older cave men went to the place where the fire had first started and gathered about the hot coals, enjoying the warmth. But soon they saw that the fire was dying out, so they began to throw leaves and twigs and branches on it, and every time it blazed up they shouted with joy.