"Hasn't your teacher at school told you what makes colors?"
"She's talked something about it; but I never saw any sense to what she was saying, and so I didn't pay attention."
"I learned about that in the primary school, but I didn't understand it very well until I read about it in my 'Science for the Young.' I'll see if I can explain it to you."
There was a rubber ball among the little boy's playthings, and Johnny asked him if he might take it a few moments. As the boy was not using the ball, he handed it to Johnny very willingly, saying, "You can play with it as long as you've a mind to."
Johnny threw the ball on the floor of the piazza in a straight line, remarking,—
"You see, Felix, the ball bounds right back to my hand, in just the direction in which I threw it down."
"That's nothing: everybody knows that a ball always does so."
"But that is just the way some of the rays of light bound back whenever they strike any thing which is not transparent; that is, if they strike it directly, or at a right angle. The rays which come back are called reflected rays. Every thing which is not transparent reflects light that shines upon it; that is, the light bounds back. It is just the same with heat: that which is not absorbed by the substance upon which it falls, bounds back, or is reflected."
"If that's so, what of it?"
"Why, that's what makes the grass green, and flowers of different colors, and your suit blue, and your necktie red, and your eyes brown: that's what makes things seem to be colored."