Étienne-Louis Boullée’s Architecture, Essay on Art conceives architecture not as the mechanical production of buildings but as an intellectual art capable of moving the human spirit through character, grandeur, light, proportion and the deliberate orchestration of affect. Against the reduction of architecture to construction, Boullée insists that the architect must first become a thinker of forms, studying nature in order to extract from it principles of order, harmony and emotional intensity. His theory therefore privileges the “poetry” of architecture: masses, shadows, vast geometries and symbolic programmes must be composed so that a building communicates its purpose before it is used. This is evident in his reflections on monuments, temples, basilicas, theatres and palaces, where each project is treated as a moral and civic instrument rather than as a merely functional object. The case of the Cénotaphe à Newton condenses this ambition with particular force: by imagining an immense spherical monument animated by cosmic light and darkness, Boullée translates scientific genius into spatial sublimity, making architecture an analogue of the universe itself. His wider lesson is that architecture achieves artistic dignity when it produces an intelligible and overwhelming impression suited to its subject, thereby fusing sensation, reason and public meaning. Boullée’s essay thus concludes, implicitly but powerfully, that architecture becomes art only when construction is subordinated to the creation of a symbolic experience capable of educating, elevating and astonishing society.