Stanley Skreslet's book, Picturing Christian Witness, (Grand Rapids, MI: Eerdmanns, 2006) devotes a chapter to this subject and questions the ways in which the role of the shepherd is, or isn't, missional.
At the end of the chapter there is a copy of Fan Pu's papercut 'The Lost Sheep' Skreslet observes:
'In the shepherd's outstretched arm, one can perceive a determination to extend the reach of Christian pastoral compassion ... The sheep is lost, without sufficient resources of its own to cope in an unforgiving environment, where brambles threaten to ensnare and immobilize disoriented wayfarers. The searcher beckons, but the picture leaves room for the sheep to react to the shepherd's gesture in the symbolic gap that separates the two figures. A positive response from the sheep depends in part on whether or not Jesus' voices has been heard in the human shepherd's call' (pp189-190).
Is Shepherd Book that sort of shepherd? Does he have a mission? Is he looking for the lost - or is he the one who is lost? Will the voice of Jesus be heard through his voice?
When asked by Kaylee in episode 1 if he is a missionary he replies:
'I guess ... I'm a Shepherd, from the Southdown Abbey ... Been out of the world for a spell. Like to walk it a while, maybe bring the word to them as needs it told.'