His immediate purpose in appointing them was “to be with him” and to be sent out to preach, to heal and to exorcise (Mark 3:14,15; Luke 9:1,2; see also Acts 1:21,22).  This was only among the lost sheep of the people of Israel (Matthew 10:6).

But his ultimate purpose extended far beyond the borders of the Holy Land.  As his Father had sent him into the world, so the time would come when he would send them into the world to be his “witnesses in Jerusalem, in all Judea and Samaria, and to the ends of the earth” and to “make disciples of all nations, baptizing them” and teaching them to obey all his commandments (NRSV, Acts 1:8; Matthew 28:19,20).

But first he had to prepare the Apostles to undertake this stupendous world role for which he had chosen them, and of which as yet they were utterly unaware.  After an interval he sent them out in pairs on a preaching and healing mission in Galilee.  One never thinks out or understands a subject as thoroughly as when one has to teach it to others, and through their teaching they themselves would deepen their own understanding of what they had learnt from Jesus, besides gaining first hand experience in public speaking.

Before they set out he had solemnly invested them with his own power and authority to cure disease.  When they found how sure and effective that power and authority was, in spite of the physical distance which separated them from him, their own relationship with him must have been deepened immeasurably in its closeness and its confidence (Luke 9:1,2,6).