Apostolic succession was established by Christ, who ordained His Twelve Apostles. To succeed them in the mission of the growing Church, “The Twelve” ordained Bishops as leaders, Priests as celebrants of the Divine Liturgy, and Deacons as servers. In turn, the Bishops ordained their successors and overseers. Development of Church governance was necessary because, even while being ruthlessly persecuted, the Church continued to advance and grow. Since the Roman Empire was divided into provinces, each with its own governor, the Church organized itself along the same lines; and the Bishops, all of whom had been ordained exactly the same way and with the same ecclesial authority, fell into four different administrative categories: Rural Bishops for medium-sized cities and their surrounding regions, Metropolitan Bishops for larger cities and their regions, Archbishops for states and provinces, and Patriarchal Bishops for large areas or countries, called “sees.” https://orthodoxreflections.com/part-vii-of-the-western-series-papal-apostacy-supremacy-and-infallibility/