Great edifices, like great mountains, are the work of centuries. Art often undergoes a transformation while they are pending, pendent opera interrupta; they proceed quietly in accordance with the transformed art. The new art takes the monument where it finds it, incrusts itself there, assimilates it to itself, develops it according to its fancy, and finishes it if it can. The thing is accomplished without trouble, without effort, without reaction,— following a natural and tranquil law. It is a graft which shoots up, a sap which circulates, a vegetation which starts forth anew. Certainly there is matter here for many large volumes, and often the universal history of humanity in the successive engrafting of many arts at many levels, upon the same monument. The man, the artist, the individual, is effaced in these great masses, which lack the name of their author; human intelligence is there summed up and totalized. Time is the architect, the nation is the builder. […]
– Victor Hugo.