Annum Ingressi, the Apostolic Letter of Pope Leo XIII of March 19, 1902, where he speaks of the enemies of the Church and the godless attacks by Freemasonry, Anarchists, the Reformation, Age of Enlightenment, materialism, destruction of marriage, family, morality, class struggle, and the remedy for these disorders.
“Having come to the twenty-fifth year of our Apostolic Ministry…”
Or read it online at www.tfp.org/annum-ingressi-apostolic-letter-of-pope-leo-xiii/.