Despite the enlargement of the upper windows and the changes made to give more light to the tribunes, none can deny that, in gloomy weather, Notre Dame can be somber and even cavernous. Yet who, of its devotees, would have it different? Supreme cathedral it is for that supremest of hymns, the _Dies Iræ_--sound and sense and vision welded. To exchange its severe majesty for an expanse of brilliant glass--save Suger's glass--is unthinkable. In Notre Dame you comprehend the spectacular repentances of the Middle Ages. Here, when pestilence stalked the city or the enemy was at the gate, have echoed the _Miserere_ and the _Libera nos, Domine_.[72] There is an individuality in the cathedral of Paris that overrides every criticism. Perpetually does the worshiper find in it new aspects, in the dim, low aisles full of mystery, in the gleam of transept windows as seen through the tribune arches while one listens, perhaps, to a lenten friar preacher discoursing of sin, justice, and the judgment to come; here on the very spot where Dominic himself taught the same sobering lessons; here where, six hundred years later, his son, Lacordaire, held the manhood of Paris spellbound. Or, again, one gazes down the length of the church, with its incomparable perspective, while around one rise the voices of strong men fresh from the battle of Verdun, fresh from their firm "They shall not pass," and their _Magnificat_ of thanksgiving to Notre Dame swells in a volume of sound like the eternal sea. The crusaders of St. Louis' time prayed, too, for strength in Notre Dame of Paris.[73] The curve of the sanctuary as seen from the west end of the nave is one of the splendors of the monument, and no chevet ever built surpassed it. The cause of the magic is practical--a structural problem solved, as is the case with the best aspects of Gothic art. At that eastern curve extra piers were inserted between the double aisles in order to obviate the difficulty of vaulting such irregular trapeze-shaped sections. The enthusiast maintains that the exterior of Notre Dame surpasses that of all other cathedrals. Certainly better transept façades were never made nor was apse more romantic than that of the chief church of Paris, as it rises in three grandiose steps, with flying buttresses of wide span leaping with an audacity that fairly catches the breath; and again the success is a case of sound science solving a problem.