St. Luke himself is the author of two books in the Bible: "The Holy Gospel according to St. Luke," and "The Acts of the Apostles." Although he did not know Jesus whole Our Lord was on this earth, he wanted to write about Him for other new converts like himself. So he talked to those who had known Jesus and he wrote down all that they had seen Our Lord do and heard Him say. It is believed that St. Luke learned from the Blessed Virgin Mary herself all about the Angel Gabriel's appearance to her, the birth of Jesus in Bethlehem, the flight of the Holy Family into Egypt, and many other facts we read in his Gospel.
Luke also wrote the story of how the Apostles began teaching the message of Jesus after Our Lord went back to Heaven. It is in his book, "The Acts of the Apostles," that we learn how the Church began to grow and spread.
St. Luke is the patron saint of doctors and of painters, too, because it is believed that he painted a beautiful picture of our Blessed Mother.
In his Gospel St. Luke wrote especially of the mercy of God for repentant sinners. Today I will read in it the parable of the Lost Sheep.