"What is that?" asked the captain, who appeared at the door. "Do you think a man's eyesight grows keener by flying, after he is at it for a time?"
"It seems so to me," answered Ralph.
The captain shook his head. "I think that is a misapprehension. The eyesight does not become sharper or more acute."
"Then how is it that I can now see things that I could not notice when we first began to fly?" asked Alfred.
"Observation! observation, my boy! You can't see one whit better today than you could the first time you went aloft," said the captain. "The eye is a very deceptive thing,—you laugh at the statement,—well, I'm going to prove it. In everything you see the judgment is not formed by what the eye tells you, but by your knowledge, your habit of observation and application growing out of previous experiences."
"Pardon me, Captain. Do you mean to say that the eye doesn't correctly tell you distance or size or what the object really is?" asked Alfred.
"That's exactly what I mean," replied the captain.
"Well, that's a new idea to me," said Ralph.
"Suppose we examine that. I have an article here,—a box, in my hand. Tell me, Ralph, how large it is, what it is made of, and what it is used for?" said the captain.