Before the Flamboyant Gothic transept of Beauvais was finished, the foreign Renaissance had arrived in France. And it showed here in the richly sculptured doors. The sibyls, all ten of whom are represented, are, as pagans, kept outside the church. With skilled gradation the carving grows deeper and bolder toward the top of the doors, farthest away from the eye. Jean Le Pot carved the southern doors in faultless taste. He was a glassmaker as well, and in St. Étienne's church are his windows beside those of his father-in-law, Engrand Le Prince, who, with his sons Jean and Nicholas, made the north and south rose windows of the cathedral and its splendid Peter and Paul window. Their tree of Jesse, in St. Étienne's choir, is considered a masterpiece of color and design. To-day a Le Prince window in any French city is a matter of civic pride. The old saying ran: "The choir of Beauvais, the nave of Amiens, the portals of Rheims, the towers of Chartres" make the most beautiful cathedral in the world. One hundred and fifty feet high curve the upper vaults of Beauvais choir. Beneath them could be set the belfries of Notre Dame of Paris. As at Bourges, the lofty aisle possesses its own triforium and clearstory, but here the clearstory of the central choir has not been dwarfed as a result of the stupendous pier arcades. Beauvais dared to make its upper windows eighty feet high. Think what its interior would be had it retained the original stained glass! Its towering choir windows would scintillate like those of Sainte-Chapelle, since it was the Paris school that supplied XIII-century Beauvais. Such a sweep of fragile glass was possible because the play of thrusts and counterthrusts had been calculated to a certainty. Technically, Beauvais is the extreme expression of the Gothic theory. It perfected the pier by making it elliptical, widest where fell the greatest strain, north and south. It is said that its error lay in certain false bearings, that some of the intermediate buttresses were balanced half on air without direct ground supports. That may have been temerarious, since building material of perfect quality is required when chances are taken. Certainly Beauvais pushed to its rigid consequences the law of equilibrium, allowing no excess in the supporting members, but it was not a builder's folly. M. de Lasteyrie has called its plan a _chef-d'oeuvre_ of lightness. Though the architect pushed his technique to the extreme limit of the law of thrust and counterthrust, he did not pass beyond the possible, and had he employed the hard, resistant stone of Burgundy the history of the cathedral church he built would not be a tale of disasters. What brought about the collapse of Beauvais' vaults was the use of inferior stone.