The author talks about how Notre-Dame has changed over the centuries due to the work of Time, religious revolutions, and restorations.
The author thinks restorations are the worst kind of change because they're done consciously. It's clear that he doesn't like some of the ways architects have changed parts of the cathedral.
Notre-Dame is not just in one style; it's in a transitional style, a combination of many different styles. The author says that such works are not the works of one genius; they're the works of the people and of society.
Even though the surface of Notre-Dame may change throughout the centuries, at its core it's still a church.
Chapter 2: A Bird's-Eye View of Paris
The author describes what the Paris of the 15th century would have looked like from the view of Notre-Dame's towers.
Paris started out just on the island of the Cité, but it outgrew the island after a few centuries.
In the 1400s, Paris was divided into three parts: the Cité on the island, the Université on the left bank, and the Ville on the right bank. Even though these areas are distinct, they form a single connected body.
The author then describes (at length) the views offered of each of these three areas. Basically, the Cité is the oldest-looking, the Université is more geometrically uniform and beautiful, and the Ville is where the upper crust have their palaces.
The Paris of the 15th century was beautiful because it was uniform, but according to the author, this uniformity has been gradually chipped away after the Renaissance period and replaced with nothing in particular. It's now a jumbled mess of too many styles. Oh, well: c'est la vie.
But, says the author, try to put yourself in the Paris of the fifteenth century, and imagine waking up to the sound of all of the bells ringing from every steeple. Together, these bells create the harmony of the city.