Mary's birth is a sure sign of new times

A less solemn feast than the Assumption, the Nativity of Mary is joyfully celebrated by Christians, like the birth of John the Baptist. Both births herald the dawn of salvation. In the liturgy, Mary's birth and her future divine maternity are connected. 

The Church of Jerusalem was the first to honor the memory of the Nativity of the Mother of God, with a feast that Rome probably adopted towards the end of the 7th century, when Pope Sergius I endowed it with a procession.

Mary's birth is a sure sign of the new times. The Old Testament comes to an end, and finds its fulfillment in a new and eternal pact that God makes with mankind. 

Joy is the keynote of this feast. All generations call her blessed, this Virgin who bore the Son of the eternal Father. This feast is also celebrated by Eastern Churches.

Taken from the official website of Notre Dame de Paris Cathedral 

www.notredamedeparis.fr