Johnny began to laugh.
"Why, of course they are not hot until they begin to burn; if they were, you couldn't say that the heat was stored up; it would be escaping all the time: and then, wouldn't it be dreadful to have the trees hot instead of making a nice cool shade? and how could the miners get the coal if it were hot? and how could we carry fuel about from place to place? and we should have to be made like salamanders, if every thing around us that the sun had put heat into was hot: we couldn't sit at this table, or in these chairs, or handle these books; and the floor would burn our feet, and our clothes would feel hot."
"My clothes do feel hot," said Felix, beginning to laugh, also, at Johnny's vivid picture of what would be if the sun had not locked its stored heat up so coolly and comfortably for our use.
"It isn't your clothes that are hot, though, unless your body has heated them, or you have been sitting or standing in the sun; it is you who are warm, and your clothes keep the heat that comes from your body from passing freely into the air: your clothes themselves are not any hotter than they would be if they were in an ice-chest; that is, I mean the heat that the sun has stored in your clothes would be every particle there if your clothes were kept next to ice."
"I'd like to know, now, how you make all that nonsense out?"
"Heat is force: in one sense, the heat of the sun is the force of the sun. Now, when things are growing, the force of the sun goes into them in some way, and makes them take carbon out of the air, and hydrogen out of the water in the ground, and from the rain and dew: and just exactly as much heat or force as the sun has put into a tree or plant, or any thing else, can be got out of it by causing it to burn; that is, making the carbon and hydrogen contained in it, unite with the oxygen in the air.
"I don't wonder the boys call you professor," said Felix: "I'd like to know how you ever got to know so much about every thing. What you say is a great deal harder to believe than fairy-stories: I guess I'll go to believing fairy-stories."
Johnny laughed again.
"Because some very strange things are true, that is no reason every thing strange should be true, or why some things should be true that wouldn't be so very strange. Do you like fairy-stories?"
"Yes, I like them as well as any thing: I've never read many stories but fairy-tales. Story-books are all lies; and if I'm going to read lies, I'd rather read some good big ones."