THE HISTORY OF GOTHIC ARCHITECTURE
THE Gothic style evolved from within Romanesque church architecture when diagonal ribs were added to the groin-vault.
In common usage, any kind of arch which lies within the surfaces of a vault is called a rib. So, also, is the ridge-rib, which appears later, and is not in fact an arch at all. In our consideration of the beginnings of the Gothic style, we need for the moment concern ourselves only with those ribs which are arches.
Suger, abbot of St Denis, who in about 1144 was the first man to write about the Gothic style, called the rib arcus, the same term which was used for any other arch.1 Gervase of Canterbury, about 1180, used the expression fornices arcuatae, or arched vaults. About 1235 Villard de Honnecourt was the first to use the word ogive, which, after being incorrectly used for several decades during the nineteenth century to mean the pointed arch as well, has remained the French term for a Gothic rib to our own day. The word ogive is generally derived from the Latin verb augere (to strengthen), and this derivation corresponds to the belief that the purpose of these arches was to reinforce the vault. Some philologists say that the word originates from algibe, the Arabic word for cistern, and that it did not, therefore, apply to buildings with rib-vaults, but to those with groin-vaults, and more particularly to Spanish cisterns.2 It is unlikely that Villard borrowed the word from Spanish. In English, arches within the surfaces of a vault are called ribs, in German Rippen, in Italian costoloni: all these words suggest a similarity to the human and the animal skeleton, which also has a function in terms of statics. In English literature on the Gothic style, the words rib and groin were sometimes used synonymously, which makes for unnecessary confusion. The word groin in this book means only the one-dimensional or linear edge where the curved surfaces of a vault penetrate one another, while rib means only the three-dimensional arch within the surfaces of a vault.
After 1835, when Johannes Wetter declared the rib to be one of the integrating members of the Gothic style, it became more and more the centre of discussion. The question of the date of the earliest ribs appeared so significant because it seemed that the correct answer to it must surely lead to the discovery of the birth date of the Gothic style. Instead it was found that ribs had already been used in Roman buildings. These ribs have never been fully studied. Two or three examples will here be sufficient. A