Antoni Gaudí was aware that he would not complete the project for the whole church, and so he organised it and the construction so that it could be carried out following his ideas. He programmed the construction, not building all the walls to the same level at the same time but in complete parts (façades, naves of the interior and towers), so that each generation would be the protagonist of one part. He defined the project as a whole on ground plans, sections and elevations and specified important parts in scale plaster models that defined the project in detail and had to serve as models for other parts; for example, the 1:10 scale model of the main nave was used for its construction, but also for the definitive project of the vaults of the crossing and of the apse, defined generally in the sections. Moreover, he explained the project to his associates and various young architects.
To help with the interpretation and the construction, on the project he only used geometrical forms and established all the laws of the relation between them. Geometry has made it possible to discover the original project and orient the process of the rest of it and of the construction.