Mr. Laurence shook his head, smiling. "People often make that mistake," he said. "It is not smoke, but mist, or cooled steam. It is made of fine floating particles or specks of water. Smoke is made of little floating particles of charcoal. Quite a different matter, you see."
He had a short clear sort of way of saying such things, which stuck firm in one's mind; and I used to think over his words afterward, and not forget them.
"But all those clouds may not be made of mist," he went on. "Those little white streaks, far beyond and not seeming to move, are most likely made of snow. Yes, even in summer," said he, as I couldn't help showing how astonished I was. "So high up in the air as that is always intensely cold. There can scarcely be a doubt that those little clouds are frozen."
Another day he came into the garden with a little stone in his hand, hard as rock, but marked like a shell. He showed it me, and said it really was a shell, only very very old, and turned into stone. He called it a "fossil," which was a new word to me then.
"Where do you think I found this, Miles?" asked he.
"I don't know, sir," I said.
"Not on the sea-shore, but on the top of the cliff, buried deep. How do you think it came there?"
I couldn't tell, of course.
"Once upon a time, ages ago," said he, "those cliff-tops were under the waves. Not that the sea was higher, but that the land was lower. Once upon a time all England was deep under the sea, and the ground rose up very slowly to its present height. So you see how easily sea-shells can have become embedded in the highest rocks."
I had been doing a good deal of cloud-gazing for many days, picturing to myself how strange it was that all those wonderful shapes should be made of mist or snow. The next thing I did was to spend my spare time wandering about the cliffs, hunting for fossils above, or looking up from below and trying to fancy how all those heights had been once under the sea.