Today is the memorial of the Blessed Virgin Mary mother of the church. In the 4th century, Saint Ambrose of Milan first referred to the blessed mother as the Mother of the Church, but somehow the title and reference became lost and unused until the 20th century when it was rediscovered by a German Jesuit, Hugo Rahner, older brother of Karl Rahner. 

Then in 1964. As he was closing the 3rd session of the 2nd Vatican Council, Pope Paul the 6th in his credo of the people, made the title official. He said we declare Mary the Most Holy Mother of the Church that is of all Christian people. 

Saint Pope John Paul II placed it in the Catechism of the Catholic Church and Pope Francis added it to the Roman calendar. 

Blessed Virgin Mary, Mother of the Church, please pray for us.