From Champagne came the gracious arrangement of planting slender columns and stilted arches at the entrance to radiating chapels. Champagne was the first to use the pier composed of twin columns, first to employ a passageway round the church at the level of the aisle windows, and to place lancets side by side in each bay for the better lighting of the edifice. The region was conservative in clinging to certain Romanesque traits, such as apsidal chapels projecting from the eastern wall of the transept. It employed, as did Normandy and Burgundy, a circulation passage under the clearstory windows. Champagne's influence spread far afield to Sens, Auxerre, St. Quentin, St. Denis, Metz, Toul, Ipres, Tournai, Avila, León, and York.[151] Lest these pages should become overloaded, we can merely touch on the beautiful Champagne cathedral of Châlons-sur-Marne, an old city which is another treasure house of colored glass. The most interesting windows are in the small church of St. Alpin, whose apse celebrates the Eucharist, the souls in Purgatory, the Corpus Christi procession, lately mocked by the Calvinists. Its Manna in the Desert window is a symbol of the Eucharist. In St. Alpin are the most successful examples of that distinguished phase of vitrine art called _camaïeu_--of cameo or chiaroscuro effect, using brown-gray hues, the yellow of silver-stain, a pale blue for the sky, and an occasional single touch of superb ruby red. One of the windows of Raphaelesque design represents St. Alpin, bishop of Châlons, meeting Attila the Hun; another, dated 1539, is a rendering of the Vision of Augustus, a theme most popular then. Peter the Venerable called Châlons "great and illustrious." Guillaume de Champeaux, one of the most learned men of the age, whose schoolroom was really the beginning of the University of Paris, was bishop of Châlons in 1115 when a young Burgundian named Bernard came to be consecrated abbot of Clairvaux. In the monk of twenty-five, unknown yet to fame, the great teacher was swift to recognize a supreme spiritual genius. In 1147 St. Bernard preached at the dedication of the Romanesque cathedral of Châlons before Pope Eugene III, who had been one of his own Cistercian monks at Clairvaux. The present tower to the north of the choir belonged to the church that Bernard knew. The south tower, its mate, is of the XIII century. The placing of belfries on either side of the choir was a Rhenish trait.