The great geometric schema allowed the masons to stake out the site (the plot) and control the overall shape of the cathedral over the extended period of construction.   Individual forms (pier and arch profiles, window tracery, etc.) were fixed through the application of rigid wooden templates as stone production was increasingly rationalized.  All concave surfaces (arches, vaults) were formed over rigid wooden centering: the carefully-cut stones were laid up with a thin layer of mortar, left in place for a period (a couple of months or so) and then the formwork was removed.  The concave surface may thus be understood as an impression of a shape that has, in a sense, been printed upon the masonry.  This technology facilitated the unfolding of an extended building with an extraordinary level of accuracy where all details can be controlled.  There is obviously an underlying theological message: the forms of the cathedral have been stamped out like the Apostles in the central portal who followed the prototype provided by the image of Christ.  Yet there were two forces capable of countering this level of perfection.  First, in the creation of this awesome space, artisans and clergy were conspiring to reach the Sublime: the projection of vaulted masonry canopies up to an unprecedented height.  Within the arched masonry forces were at play that were capable of destroying the rectitude of the edifice, pushing verticals out of plumb and threatening disaster.  Such forces were built into Amiens Cathedral, especially in the oversized bays adjacent to the crossing.  Within two centuries the crossing piers were threatening collapse.  In our website, to use the simulation of the dynamic behavior of arched masonry you must open in Safari not Chrome.

The second force capable of impinging upon the perfect uniformity of the cathedral was critical choice.  Whereas Thomas de Cormont, the second master, was content to follow Master Robert de Luzarches's forms, the third, Renaud de Cormont, thirty years after the start of work, introduced radically new forms (glazed triforium; openwork flyers) in the upper transept and choir.  Renaud played Icarus to Thomas's Daedalus.