St. Peter Canisius (1521-1597) was born at Nijmegen, Holland, at the very time that Luther began to rebel against the Church and St. Ignatius Loyola was laying the foundations of the Jesuit Order. After studying the arts, civil law and theology, St. Peter joined the Jesuit Order and was ordained a priest in 1546. He is noted especially for the following services to the Church: he defended the Catholic faith against the Protestants; by preaching, writing, founding colleges and seminaries, he caused Catholic life to flourish; he rendered invaluable services to the ecuмenical Council of Trent; he wrote many Catechisms which were translated into twelve languages in his own life time. He died in Fribourg, Switzerland.

According to the 1962 Missal of Bl. John XXIII the Extraordinary Form of the Roman Rite, today is the feast of St. Thomas, now celebrated July 3. Previously St. Peter Canisius' feast was celebrated on April 27.

Today is the fifth of the O Antiphons. It is the Sun, the Redeemer, whom we await. "I am the light [the sun] of the world" (John 8:12). Christ is the light of the world because of the faith which He has infused into souls. He has enlightened the world by His teaching and by the example of His life. In the crib, in Nazareth, on the cross on Calvary, in the tabernacle of our churches, He answers the eternal questioning of the benighted soul.

http://www.catholicculture.org/culture/liturgicalyear/calendar/day.cfm?date=2013-12-21