When the little Water Spiders first opened their eyes, and this was as soon as they were hatched, they found themselves in a cosy home of one room which their mother had built under the water. This room had no window and only one door. There was no floor at all. When Father Stickleback had asked Mrs. Spider why she did not make a floor, she had looked at him in great surprise and said, "Why, if I had built one, I should have no place to go in and out." She really thought him quite stupid not to think of that. It often happens, you know, that really clever people think each other stupid, just because they live in different ways. Afterward, Mrs. Water Spider saw Father Stickleback's nest, and understood why he asked that question.