The word Intercession comes from the Latin meaning "to stand between." Intercession is quite different from ordinary prayer. It carries with it a priestly function and duty and since all Christians are or should be priests it follows that all Christians have the capacity to be intercessors. However just as the Bible required training before the Israelite priests could take full responsibility at the age of 30 so also with intercessors. They must come to some level of spiritual maturity before they can really be effective in that type of ministry. The sons of Aaron however entered into apprenticeship at the age of 20 which lays down the principle that an intercessor (or priest) must undergo some on-the-job training.