Death of Pope Urbanus VI, 202nd successor of Peter whose pontificate lasted eleven and a half years. He was the first Pope to be elected by a conclave held in the Vatican after the seventy years captivity in Avignon. Yet, he could not avoid the creation of antipopes at Avignon and this brought about the Western Schism which would last forty years. Many believe the weight of this sorrow bore heavily on his death.
First day of the new Gregorian Calendar which was introduced in Italy and other Catholic countries. In order to make the transition from the old Julian Calendar to the new one authored by Pope Gregory XIII it was necessary to eliminate ten days. Thus, when people went to sleep on the night of the 4th in 1582, the next day they woke up was October 15th.
Death of Saint Teresa of Jesus from Avila, Spain who was so instrumental in reforming the Carmelites and spurring on Saint John of the Cross to do the same for the priests. For more on this first female Doctor of the Church, see THIS WEEKEND'S LITURGY.
Pope Leo XIII issues his encyclical Dall' alto Dell' Apostolico seggio intended primarily to the Italian bishops and their flocks on the evils of Freemasonry.
Pope John Paul II issues his 13th encyclical Fides et Ratio on the eve of his 20th anniversary in which he deals with "Faith and Reason" covering issues which many call his "last will and testament" on the fundamental questions of human existence.