The nave of Saint Germain-des-Prés, is an example of the heavy-pillared, round-arched building of the Romanesque era. The desire to give visible form to the universal feeling of uplift brought to birth the ogive or pointed arch which gave its name to “ogival” or Gothic architecture best shown, of course, in churches. Higher and higher the arches pointed skyward; lancet windows above helped to light the deep “vessel” or nave (from the Latin _navis_, ship) and the roof crowned all at a dizzying height. Satisfying as this was from the point of view of beauty and of symbolism, it gave rise to serious practical questions. How were such lofty walls to be made strong enough to support the outward push of the roof? The thirteenth century had come about before the problem was solved entirely. By that time outer buttresses had been evolved strong enough for their work yet so delicate that they were called “flying,” spread as they were like the wings of a bird. Decoration became more beautiful, also. Romanesque pillar capitals had been adorned with conventional vegetation and strange beasts whose originals never were on land or sea. The sculptors of the ogival period took Nature as their teacher and France as their schoolroom and carved the leaves and flowers and fruits that grew about them, the oak and willow and rose-bush and clover and grape. Pinnacles gave an effect of lightness to exteriors and their edges were [Illustration: CHOIR AND NAVE OF NOTRE DAME, LOOKING WEST.] [Illustration: NAVE OF SAINT GERMAIN DES PRÉS.] decorated with _crochets_ (furled leaves) and tipped with _fleurons_ or bunches of budding leaves. High heavenward sprang spires from the western end of the churches, this western façade forming an imposing entrance to the nave through whose length the choir and altar at the eastern end, beyond the transepts, looked mysteriously far away. From the roof at the junction of the nave and the transepts a slender spire called a _flèche_ (arrow) shot upward with exquisite grace. The introduction of ogival architecture had a sudden and revolutionary effect upon the art of painting. Before the twelfth century mural decorations and the illumination of manuscripts had been the only instances in France. When the broad expanses of wall above the semicircular Romanesque arches vanished with the coming of the pointed arch there was no place left except the windows for the depiction of the lives of the saints, of scenes from Old Testament history and from the life of Christ. Glass then became the artist’s medium. The most illustrious examples of the new style to be found in modern Paris are the cathedral of Notre Dame, the refectory of Saint Martin-des-Champs, and the Sainte Chapelle built by Saint Louis in the thirteenth century.