In their efforts to protect their churches by masonry roofs, these various regional schools made use of the barrel vault or the groin vault. The latter was found too insecure to span a wide space. Now, the thrust of a barrel vault was exerted along the whole length of the wall, which necessitated a continuous abutment—in other words, an enormously thick wall. Only small windows could be opened. Since the Romanesque architect had the ambition to light his church well, and not to encumber his floor surface by clumsy piers, a barrel vaulting could be but a temporary solution of the main problem.
The struggle for a satisfactory stone roof was pursued tenaciously. Many a clearstory wall was thrust apart by the vaulting’s pressure. Thus the abbey church of Bec, finished in the ’forties of the XI century, was reconstructed in the ’fifties, and three times, again, had to be rebuilt. No failure could daunt the courage of those old monastic builders. Already inherent in the newly amalgamated race was the creative genius of France. Perseverance and courage were to have their reward.
The theory long taught in the École des Chartes was that in the first part of the XI century, among a number of rural churches in the royal domain, there gradually came into use the member which was to revolutionize the science of building. The idea did not spring from one brain; it was a collective, not an individual, triumph. When, under some groin vault, no doubt at first to reinforce it, some obscure mason constructed the earliest intersecting stone ribs, the first step in Gothic architecture had been taken.[11]
From that essential organ, the other characteristics of Gothic art were deduced: flying buttress, slender piers, expanse of windows. In a Gothic vault the infilling, or web, rested elastically on the diagonal ribs. As the load of the stone roof was thus concentrated at fixed junctures, it was necessary to reinforce only those given points. Buttresses became intermittent. All the disintegrating force of the heavy vaulting was gathered on the diagonally crossing arches. An arch never sleeps, said the old Arab proverb. Let us then, said the mediæval architect, set a guard on it that also never sleeps; and from that idea he proceeded to develop the greatest architecture of all times. The force of expansion was counteracted by a proportionate force of compression. By means of a framework made up of vault ribs, of piers, of buttresses, and flying buttresses, the edifice became a living skeleton. The walls between the active members, when relieved of their load, served merely as screen inclosures and could be carved into fragile beauty and hung with transparent tapestries of colored glass. Because the flying buttress transmitted a large part of the vault’s pressure to the exterior buttress piles, the piers within the church could be lessened in diameter, and greater capacity be given to the interior.
Each new trial was a lesson learned. It was only with time that they adjusted precisely the sufficient counterpoise to the thrust of the vaults; it was only by degrees that the pier’s diameter was lessened, only with practice that was learned the placing of flying buttresses neither too high nor too low. At first many a flying buttress was made needlessly heavy. The solid wall in between the buttresses was not discarded all at once. In the first Gothic churches windows continued to be single lights, then two or three lancets were placed side by side, subsequently each light was subdivided by mullions, and gradually an elaborate fenestration developed. For a time, too, the round arch continued in use, and the earliest vault ribs were semicircular. With the fusion of the equilateral arch and the counterbutted intersecting ribs, the essence of Gothic architecture was achieved.
Lesser consequences of the new form of vaulting followed in logical succession. Obeying the law that it is the thing borne which commands the form of the thing that bears, the ribs may be said to have drawn out of the sturdy pier of Romanesque art the clustered columns of Gothic gracefulness.
Not a single beauty in a Gothic church but has a structural explanation. The soaring pinnacles that crown the buttresses are apparently mere ornaments, but in reality those gallant little bits of decoration are of sound engineering usefulness. By weighting the buttresses, they hasten to channel the transmitted lateral thrust of the vaulting into a vertical pressure, and they increase, too, the counterthrust of the flying buttress against the side walls.
A clear comprehension of Gothic is impossible unless the fact be grasped that architecture is nothing if not structural, and that no decoration can veil a faulty skeleton. Ornamentation is the spontaneous blossoming of the structure, else it is meaningless—a principle many a modern architect might well digest. Too long has the most scientifically exact of architectures been judged by its embellishments, which often enough, in the hands of the copyist, do become a florid veneer without reason.
The Gothic master-of-works was right when he said that nothing which was inherently needed could be ugly. No longer were flying buttresses hidden under the cover of wooden roofs. Proudly ranged about the church, those essential practical members became one of the distinctive beauties of the new science of building. Renan, with his treacherous half praise, has called the flying buttress a crutch needed by an architecture which, from its start, nourished the seeds of decay, since it was based on no sound constructive formula. Its success was a prestidigitator’s trick, he said. Such criticism misunderstands the A B C of Gothic lore. Can a living limb be called a crutch? it has been aptly asked. The Gothic cathedral is not only the most complicated, but is also the most complete, organism ever conceived by man.
Where the first diagonal-crossing ribs are to be found will probably never be known. Various have been the claimants. The Rhenish claim is no longer taken seriously. Gothic made its first appearance in Germany as a fully developed French art, and its XIII-century name, there, was opus francigenum. In his Gothic work the Teuton showed a fondness for the tour-de-force and his manual dexterity surprises more than it satisfies. The best German works in architecture are the sober Romanesque churches. Germany’s school was developed a century before the Romanesque of France; across the Rhine occurred no Norman invasion to sever art traditions from Charlemagne’s renaissance. The pre-Gothic art suited her ethnical temperament, and was long adhered to. While France was building Gothic, Germany was still erecting Romanesque cathedrals. Not till the end of the XII century were churches along that “rue des moines,” the Rhine, vaulted in the new manner.