Luke was a Greek physician who wrote the Gospel of Luke and the Acts of the Apostles. Unlike Matthew and John, Luke did not observe the events of Jesus's life first hand, but relied upon eyewitness accounts. And unlike Matthew who wrote for a Jewish audience, Luke wrote for a Gentile audience.
Since Luke was a highly educated man, his gospel is very detailed and comprehensive. Archaeologist William Ramsay said of Luke:
Luke's history is unsurpassed in respect of its trustworthiness ...
Luke is a historian of the first rank; not merely are his statements of fact trustworthy ... this author should be placed along with the very greatest historians.
The quality of Luke's writing is superb, second only to the flawless, spectacular Greek of the Epistle to the Hebrews. Many of the passages in Luke's books, such as the Prodigal Son and account of the encounter on the road to Emmaus, are some of the most beautiful written works in all of world history.
St. Luke’s icons
According to a tradition, the Evangelist St. Luke was a talented painter as well as a physician. He painted an icon presenting the Virgin Mary holding the Child Jesus, which many churches all over the world later on copied. Also, in a reference, it was mentioned that the historian Van Celub found an icon of the Archangel Michael during his visit to a Cathedral in Alexandria, that was also made by the Apostle Luke. 
According to legend, St. Luke had a vision in which the Virgin Mary with the Christ child appeared to him. The evangelist recorded his vision in a painting, which led to him being considered the patron saint of painters. 
- Easton's Bible Dictionary, article on Luke originally published in 1897.
- Sir William Ramsay, The Bearing of Recent Discovery on the Trustworthiness of the New Testament (Grand Rapids: Baker, 1953), p. 222. ISBN 978-0801076770 (quoted at )
- Sir William Ramsay, St. Paul the Traveller and the Roman Citizen (Grand Rapids: Baker, 1962), p. 81. (quoted at )
- Rare Portraits of the Blessed Virgin Mary
- St Luke Painting the Icon of the Virgin