Their evolution is interesting and curious. At first we find them as screens of pagan and Roman origin, and dating back to the middle of the twelfth century. But the pagan screens were adapted by Christians, who gave to them the name diptycha of the Apostles, of the Martyrs, and of the Saints, and used them as portable altars, and also largely as votive gifts, their richness being in proportion to the wealth of the giver and the importance of the subject depicted. We have several examples in the Camara Santa of Oviedo Cathedral and in the Camarin of Santa Teresa, Escorial (Plate 55). The Tablas Alfonsinas in the Sacristia Mayor of the Cathedral of Seville is another and more important example. This treasure is specially interesting, as it shows the actual use made of these folding tablets. It was the altar of Alfonso the Learned, and was presented by him to the cathedral in 1274 after he had used it in battle; for in Spain these altar-screens were carried by Christian generals travelling in the campaigns against the Moors. As the Reconquest progressed their importance increased, and we have triptycha and pentaptycha as well as diptycha; their number multiplied as they became richer and grander in ornament. They were connected with the deepest religious feelings of Christian Spain, being used by the Paladins to pray to before plunging into battle. Later, from portable altars they became fixed altars in churches. From this time their size and magnificence increased, the religious sentiment associated with them explaining, as we believe, both their frequency and their importance in the art of the period. A selection of the most admirable altar-screens alone would make a long list. Almost every church and all the great cathedrals furnish examples; they are especially numerous in the churches of Catalonia and Navarre. The altar-screen in the Romanesque church of San Feliú, though less known than those of Zaragoza, Barcelona, Tarragona, Pampeluna, and Burgos, is important as a very beautiful and early example of these retablos. It is in two distinct sections, which stand upon a widely spreading base. The first or central part is in three storeys, which are supported by Gothic pillars, and in the nine niches stand statues of the saints. These, as well as the bas-reliefs and carvings on the pillars, are of great vigour, and the effect is strengthened by the admirable painting and gilding. The second part of the screen is composed of two wings, on which are carved the figures of the prophets, surrounded by rich foliage. These too are painted and gilded.