Étienne-Louis Boullée Nationalbibliothek

Boullée promoted the idea of making architecture expressive of its purpose, a doctrine that his detractors termed architecture parlante("talking architecture"), which was an essential element in Beaux-Arts architectural training in the later 19th century. His style was most notably exemplified in his proposal for a cenotaph for the English scientist Isaac Newton, which would have taken the form of a sphere 150 m (490 ft) high embedded in a circular base topped with cypress trees. Though the structure was never built, its design was engraved and circulated widely in professional circles. Boullee's Cenotaph for Isaac Newton is a funerary monument celebrating a figure interred elsewhere. Designed in 1784, for all its apparent originality, it actually derives from contemporary archaeology. The small sarcophagus for Newton is placed at the lower pole of the sphere. The design of the memorial creates the effect of day and night. The effect by night, when the sarcophagus is illuminated by the starlight coming through the holes in the vaulting. The effect by day is an armillary sphere hanging in the center that gives off a mysterious glow. For Boullée symmetry and variety were the golden rules of architecture.