By two and two (duo duo). This repetition of the numeral instead of the use of ana duo or kata duo is usually called a Hebraism. The Hebrew does have this idiom, but it appears in Aeschylus and Sophocles, in the vernacular Koin (Oxyrhynchus Papyri No. 121), in Byzantine Greek, and in modern Greek (Deissmann, Light from the Ancient East, pp. 122f.). Mark preserves the vernacular Koin better than the other Gospels and this detail suits his vivid style. The six pairs of apostles could thus cover Galilee in six different directions. Mark notes that he "began to send them forth" (hrxato autou apostellein). Aorist tense and present infinitive. This may refer simply to this particular occasion in Mark's picturesque way. But the imperfect tense edidou means he kept on giving them all through the tour, a continuous power (authority) over unclean spirits singled out by Mark as representing "all manner of diseases and all manner of sickness" ( Matthew 10:1 ), "to cure diseases" (iasqai, Luke 9:1 ), healing power. They were to preach and to heal ( Luke 9:1 ; Matthew 10:7 ). Mark does not mention preaching as a definite part of the commission to the twelve on this their first preaching tour, but he does state that they did preach ( Matthew 6:12 ). They were to be missioners or missionaries (apostellein) in harmony with their office (apostoloi).