The two boys were going to a children's carnival in the grand courtyard of a certain mosque. Their mothers would go with them. Hundreds and hundreds of children would gather there to make the most of this glorious spring day. Osman had looked forward to this festival for a long time. "Isn't it beautiful?" he exclaimed, when he and Selim, with their veiled mothers, entered the courtyard and joined the crowd of happy little people. The children played one game after another. The boys had their tops and marbles, and did many wonderful things with them. Of course, refreshments were plentiful; there were delicious sweetmeats, sherbets, and other things the children loved. And all the time the mothers, sitting on their gay carpets, watched the boys and girls at their play, and seemed to enjoy it as much as the little ones themselves. "I have had _such_ a good time," Osman told his father that evening. "Papa, do you remember when you were a little boy like me, and went to children's carnivals?" "Yes, as if it were only yesterday, my dear. Yet many years have passed away since I romped with my boy friends and played with tops and marbles. But I have something else to speak of, Osman. Would you like to go with me to-morrow to the mosque of Agia Sophia?" "Oh, papa, yes, indeed. I love to go with you anywhere. But it is so beautiful there, I shall be more glad than usual." Osman's people use the word "mosque" as we do the word "church." Mosque means the place of prayer. The Turks build all their mosques in the same general way. They ornament them with domes and high-pointed spires called minarets. When you visit Osman's home, you will see hundreds of these domes and minarets, for there are many mosques in his city. "Papa, where is the oldest mosque in the world?" asked Osman. "It is at Medina, in Arabia, on the very spot chosen by the great Prophet himself. A part of it is kept open to this day for all homeless people. That is, if they are believers in Mohammed. They can go there at any time and live in its shelter. It was the Prophet's wish." "It would be nice if every mosque were like that one," said Osman. "When I grow up, I hope I may go to Medina and stand in the Mosque of the Prophet. He suffered very much, didn't he, papa?" "A great, great deal," Osman's father sighed. "He received his teachings direct from Heaven. We find those teachings in the Koran, our sacred book. "Mohammed had many enemies who believed he was cheating his followers. They did not believe that Allah (God) taught him. They even said bad spirits were the cause of his teachings. His life was in danger many times. But he and his teachings were saved." [Illustration: "THEY CAME IN SIGHT OF THE MOSQUE AT LAST."] Osman's father bent his head, saying these words very slowly: "Allah is great, and Mohammed is his Prophet." Osman repeated them after him. Then both father and son sat quiet for a few minutes. When the Turk spoke again, he said: