Final answer:
The essence of great architecture, according to the Ecole des Beaux Arts, was a setting for a ritual in which people could see and be seen. Le Corbusier believed that architecture should be seen as a machine for living in.
Step-by-step explanation:
In the context of the Ecole des Beaux Arts, the "essence of great architecture" was understood to reside in the concept of architecture being a setting for a social encounter where spectators were also actors. This idea was supported by the division of the structure, which created spaces for people to see and be seen. Another influential architect, Le Corbusier, had a different perspective on architecture. He believed that a house is a machine for living in and outlined five points that made up his philosophy, including free façade and open floor plan.