"Selim, Selim, you will be late if you don't hurry," called Osman.

He himself had been ready for five whole minutes, and was becoming impatient because his little friend was not in sight. So he ran across the street to Selim's house to find out what was the matter.

"I will be dressed in a minute or two," said Selim. Osman sat down to count his marbles while he waited.

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."

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:

"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."

"I love to come here in Ramazan. The brightness dazzles my eyes. I wish I could count the great wheels of light hanging from the ceiling at that time."

Ramazan is the only part of the year when the mosque is brightly lighted. It is a strange festival, and lasts a whole month.

The days are given up to fasting, and the nights to services in the mosques, to feasts, and frolics. It is the only time in the year when Osman's mamma leaves her home after the sun has set, and goes to evening parties of her friends.

All through the month, the streets are alive each evening with lights and processions and gay parties. But from dawn to sunset the followers of Mohammed must eat no food whatever, although they may feast all night long if they wish to do so.

Rich people, such as Osman and his family, enjoy turning day into night for a while. But it is not so easy for the poor, who must work without eating through the whole day, no matter how hungry and faint they may become.