Question

In Romanesque architecture, thick walls were required to support heavy stone vaults. Because these massive walls bore the direct downward and outward lateral thrust of the ceiling, windows had to be kept small and sparse to prevent structural collapse. This layout inevitably resulted in dark, fortress-like interior spaces. By the mid-twelfth century, master builders resolved this limitation by developing the flying buttress—an exterior arched support that transmitted lateral forces from the upper walls down to heavy external piers. Because the flying buttress successfully redirected these structural loads away from the main walls, Gothic architects were able to drastically reduce the thickness of the masonry. Consequently, this structural redistribution permitted the insertion of expansive stained-glass windows, transforming dark chambers into spaces illuminated by vibrant light. However, the introduction of these external supports also meant that buildings required far more ground space, forcing urban builders to alter surrounding street layouts to accommodate the wide buttress piers.

According to the passage, Gothic architects were able to drastically reduce the thickness of cathedral masonry as a direct result of which of the following?