"Ah, we build not that way here, senorita," he said. "Three centuries did our people spend in building into St. Mark's the marble carvings brought from the East; erecting the altars; and adorning the walls. These mosaics alone it took workmen two hundred and fifty years to fashion. Venice was a rich Republic, you see, and could well afford to put into this cathedral the money she might have spent on war. Above the slabs of marble are the mosaics, senorita. So it was in St. Sofia, my father told me; the slabs of marble near the ground and the decoration above. This whole cathedral of ours is covered on all the walls with mosaics--pictures made from bits of glass put together to form scenes from the Bible or from history. Even the most ignorant people who had had no schooling could read such stories, could they not?" Jean nodded. She was dazzled by the beauty of the place--by the soft light; the walls rich in gold and color; by the many wonderful things there were to be seen. She was interested, too, in the smoothly worn, uneven floor which showed where the piles beneath the church had settled. "Mosaic makers, you know, Jean, began crude attempts at making pictures in glass thousands of years ago, for glass-making was familiar to the Egyptians as well as to the Phoenicans and Syrians. The Greeks and Romans, too, were great glass-makers. So glass-making came down through the ages. The Byzantine churches usually were lighted by a row of tiny glass windows round the base of the dome. Some of this ancient glass still remains in St. Sofia. The common way of making such windows was to cut a design in a slab of marble or plaster, and then insert small pieces of colored glass. Sometimes, too, a pattern for wall decoration was worked out by sticking fragments of glass into soft stucco. So the first mosaic work began. We can see some of it in the museums of England." "There seems to be a great deal to see in those London museums, Uncle Bob," Jean gasped.