"It is bedtime for my little boy. Good night, my child." He bent down and kissed Osman, then motioned to his waiting nurse to go with him to his room. The next day was clear and beautiful. Even the street dogs seemed quieter and happier than usual. "It is good to be outdoors in the bright sunshine," said Osman, as he walked down the street with his father. They came in sight of the mosque at last. It was not beautiful to look at, but it was very, very large. "Once there were no minarets rising from this mosque toward heaven," the boy's father told him. "Only the great dome reached upward from the roof. That was when the Christians ruled over our city and worshipped in this building. But when it came into our hands, many changes were made." "Why do we call it 'Agia Sophia,' papa?" "It is sacred to 'Wisdom,' my child. The way to wisdom must be through prayer. But here we are at the doorway." Osman and his father hastily took off their shoes and put on the big, soft slippers handed them by an attendant. Other people, who were about to enter, did the same thing. There was a good reason for this. The dust of the street must not be brought in to soil the floor or carpets. They must be kept clean. During the service the people bow their heads to the floor itself many times. "It always makes me wish to be quiet when I go there," Osman once told his mother. "I wonder how men could ever build such a great, great place of worship." There were no altars, no images, no seats. But along the walls, there were slabs of marble of all sorts and colours. Pillars of rare and beautiful stones held up the roof. "They have been polished so they shine like mirrors," thought Osman, "and they are as beautiful as gems." The floor of the mosque was strewn with prayer-rugs. They were arranged so the people who came to worship might all kneel toward the sacred city of Mecca. "It is hundreds of years since Christians worshipped here," Osman's father had once told him. "They had altars of solid gold and shrines sparkling with precious jewels. Pictures of their saints were on the walls. But we, Osman, are taught not to have such paintings. A mosque should have no pictures of human shapes, nor of any other. For it is written: 'Thou shalt not make the likeness of anything.' "When the great Sultan who conquered the Christians took possession of the city, he rode through this very building. It was crowded with people who had fled here for safety. The Sultan ordered that no blood should be shed. But he made the Christians the slaves of himself and his people. "He changed the building into a place of worship fit for followers of Mohammed, saying, 'There is no God but Allah, and Mohammed is his Prophet.'" "What was done with the altars and the images and paintings, papa?" "The altars and images were torn down. The walls were covered with a coating of reddish plaster, even as you see them to-day, and this hid the pictures from sight."