For Our Lady's birthday, I'm reading Pope St. Pius X's encyclical Ad Diem Illum. He wrote it in honor of the 50 year jubilee of the dogmatic declaration in 1854 of her Immaculate Conception. That dogma was declared by Pope Pius IX in his own encyclical, Ineffabilis Deus. If I finish reading the encylical by Pope Pius X, I will read the original declaration.