Studying a bit of the background of Luke for this meditation, he was a contemporary and friend of Paul, in citizen standing at least. I thought he was a doctor, but couldn't substantiate that. He wrote his Gospel in 80-100 C.E. so it was like us writing in the present day about WWII, though without all the literature, analysis and databases that bridge that gap for us. However, I can't decry that a good book about WWII couldn't be written in the present day. Luke used Mark's writings as a basis, then apparently added direct quotes of Jesus from another source, a sort of Bartlett's Quotations. He might have used Mark in person, other writers and teachers as well. Finally, he added his own interpretations: it is thought that Luke wanted his readers to gain a greater meaning from Christ's acts on earth, so he added interpretations that extrapolated the meaning of his acts on earth to what the meaning of the lesson to us should be. Mark was associated with Paul, in Paul's early career, then they had a falling out, and then in Paul's later life, they became full associates again. Mark wrote relatively little on the Temptation of Christ.