Luke is a historian as well as a chronicler of the life of Christ, and he ties in his narrative with the historical events of the day. Here he gives six indicators of the time that John the Baptist’s ministry began.
Ryle observes from this passage that it is the same for all ministers of God. They must not go into the Lord’s work before they are sent, for the work of the ministry is such a special and such a difficult work that nothing can be achieved with out the calling of God, because with that calling comes the personal promise that God will uphold that man in the work and enable him to overcome all opposition and hardship, as well as to equip him for the task of communicating his word.