All about the Angels:

Father Paul O'Sullivan, O.P., was born on February 7, 1871. After studying in Dublin, he went on to Rome, where he was ordained a Dominican. He then pursued a Lectorate degree for theology, which in turn prepared him for his future career in writing simple, profound books and preaching to the faithful. He is the author of How to Be Happy, All About the Angels, The Wonders of the Mass, Read Me or Rue It, An Easy Way to Become a Saint, and The Secret of Confession.
Father O'Sullivan also founded the "Catholic Printing Press" and established the Rosary Association, one of several associations he created with the Church's permission. He wrote on and had a great devotion to St. Philomena as well. He died in 1958, on the Feast of the Presentation.