“Why, they are transparent.”
“What is transparent?” asked Lucy.
“Any thing that you can see through is transparent,” said her father. “Water is transparent; glass is transparent; some ice is transparent. Now, windows are made of glass, which is transparent, for two reasons: First, in order that the light may shine in and illuminate the room, so that we can see to walk about in it, and to read, and to sew. The other reason is, that we can look out through the window, and see the scenery, and the persons pass along the street. Those are the reasons why windows are made of something transparent.
“There is also something peculiar,” said her father, “in the mode in which windows open. How do they open?”
“Right upwards,” said Lucy, making a motion with her hands, as if she was opening a window.
“And how do doors open?” asked her father.
“Right sideways,” said she.
“Now, can you think of any reason why windows should open by sliding upward, and doors by swinging out upon hinges?
“First, why shouldn’t windows open like doors, by swinging out upon hinges?”
“Why, they might get broken by the wind,” said Lucy.