"Papa," said Little Horatio, "can you explain philosophy to me?"
"Of course I can," answered his proud parent.
"Natural philosophy, my son, is the science of cause and reason. Now, for instance, you see the steam coming out of that kettle, but you don't know why, or for what reason it does so, and----"
"Oh! but I do, papa," chirped little Horatio knowingly. "The reason the steam comes out of the kettle is so that ma can open your letters without you knowing it."