"I am afraid you will be more convinced of that fact than ever when you get there," chuckled Uncle Bob. "But to return to Giusippe's mosaics. You may remember, perhaps, that when the Mohammedans invaded Constantinople and found how important a part the glass-makers played in decorating the churches, they at once handed the artisans over to the caliphs, that they might be set to work adorning their mosques. Now the Mohammedans believed it a crime to make a copy of either man or woman in a picture, a carving, or a statue. It was punishable to pay reverence to sacred figures; therefore all decoration in their churches took the form of flowers, fruit, or conventional designs. So no great mosaic pictures with figures such as these were made. Between the thirteenth and fourteenth centuries Damascus became the center of glass-making, and there are in existence in some of the museums old Arab lamps which hung in the mosques with inscriptions from the Koran engraved upon them. It is Giusippe's St. Mark's which revived the art of mosaic making, and served as the bridge between those Pagan days and the days when with Christianity the arts revived and mosaic makers began to represent in glass figures of Christ and the saints." "And then the painters came, as Giusippe has said," put in Jean. "Yes, the great artists were born, and from that time pictures on canvas instead of pictures of glass decorated the churches. But the mosaic makers did an important service to art, for it was they who indirectly gave to the world the idea of making stained-glass windows. And in Venice those who ceased to make mosaics made instead the beautiful Venetian glass of which Giusippe has told us." "And are there no mosaics made now, Uncle Bob?" asked Jean. "Yes. When in 1858 it became necessary to restore some of the mosaics in St. Mark's, a descendant of one of the old Murano glass workers named Radi, together with a Dr. Salviati, started a factory on the Grand Canal, where they gradually revived some of the past glory of Venice. They copied the old time glass products, making Arab lamps such as hung in the mosques; cameo work similar to the Naples and Portland vases; and pictures in mosaic. It was they who did The Last Supper for Westminster Abbey, and the mosaics for Albert Memorial Hall in London." "But Salviati's mosaics were not like those here, senor," put in Giusippe, "because the San Marco mosaics were constructed upon the walls, small cubes of glass being pressed into the moist cement to make the picture. This gave a rough, irregular surface which artists say is far more artistic than is Salviati's smooth, glassy work. When Salviati sent mosaics away he made them here, and then backed them with cement so they could be placed on a slab of solid material and transported great distances from Venice. His pictures, it is true, were far more perfectly done than were the old mosaics--too perfectly, I have heard glass experts say."