Gothic architecture was created in France in the century or so before 1240. This was one of the most extraordinary moments in cultural history, when a traditional society entirely remade its own image. It was a process of redefinition that has never occurred, before the great creative acts of our own times.

There is no complete record of that architecture. Excellent studies have been made of particular buildings, and the general outline of the evolution of gothic has been well-popularised. But this is all based on a flimsy foundation: of 1500 buildings built in the Paris Basin during this time, parts of only twenty can be dated with any certitude. We do not have a comprehensive chronology, and as a result no one has been able to write a coherent history. The steps that led to the creation of the gothic style are understood only in the broadest outlines. The details are lacking.

The first aim of this thesaurus is to provide illustration of the 700 more significant buildings, with general photographs, description of construction, drawings of profile and all the carved capitals.

The second aim is to develop a consistent chronology from a rigorous analysis of all the surviving evidence, within the few boundaries established in the documents. After many visits to all these buildings over thirty-eight years I became convinced that only capitals could be relied on to provide this chronology. Without a chronology there is no history. It is for this reason that the first five volumes concentrate on this carved work.

The third aim is, from this chronology, to identify the time and place for each of the creative inventions that produced Gothic.

Volumes 1 and 2 covered the years from the 1170s, when the foliage was transformed from formal to natural, to the completion of la Sainte-Chapelle in the 1240s. Photos of some ten thousand capitals were included, and over three hundred relevant documents were translated.

Volume 3 has the capitals from all the buildings up to the transformation of the 1120s, when carving in archaic style became formal. This will have about five thousand photographs.

Volumes 4 and 5 will include thirteen thousand capitals from the formal period, from the first transformation that began around 1120 to the end of the second in 1180.

Volume 6 will provide an analysis of this sculptural collection and the identification of some of the most creative individuals. It will include an analysis of work practices on large sites to understand their contractual methods, and descriptions of the sculptured portals. The chronology from the previous volumes will supply a graphic reassessment of their changing views of sculpture.

Volume 7 applies this chronology to the invention and evolution of the rib vault from the early 1080s to Saint-Denis in the 1140s. This invention, that at first was used as a decorative device, had the most powerful long-term influence on the nature of architecture and the builders who created it.

Volumes 8 and 9 will concentrate on the master masons themselves, their methods and identities with an attempt to write a coherent history of the creation of the gothic style based on the previous volumes.

It is my intention to create, with both visual and written information, a solid foundation for all future studies of the architecture of this most creative period. These volumes will be a resource for restoring existing churches and for building new ones. The enormous range of medieval creativity may offer endless stimulation for artists in other disciplines. These books should certainly be in libraries and in every town with any medieval architecture.