John Kilgallen, «Martha and Mary: Why at Luke 10,38-42?», Vol. 84 (2003) 554-561

Given that Luke has wide freedom to arrange his stories as he thinks best, one looks to the material surrounding the story of Mary and Martha to better understand why that story is in its present place. It seems best to think of this story as an affirmation of the teaching of the ‘one thing necessary’, the teaching within the story of the Good Samaritan. Indeed, the Mary-Martha story underlines the Lucan emphasis on the primacy of all Jesus’ teaching.

of these two stories is, primarily, Luke’s concern to highlight the teaching of Jesus at 10,25-37 as worthy of all one’s attention, as a significant part of the ‘one thing necessary’, and as the revelation of the Father whom no one else knows as does Jesus, and, secondarily, to teach that the motivation of all Christian moral action is supremely the teaching of Jesus.