ISB ~ 1 Timothy 3 v1

bishop:An overseer or spiritual shepherd who carries on the mission of the original apostles. Note that the titles “bishop” and “elder/presbyter” were somewhat fluid in the earliest years of the Church, and it seems that they could be used interchangeably (Acts 20:17, 28; Tit 1:5-7). Soon, however, the distinction between bishops (1 Tim 3:1), elders (5:17), and deacons (3:8) was clearly defined and their respective titles were standardized.

• As if to say that the traditions of the apostles were taken from the Old Testament, bishops, presbyters, and deacons occupy in the Church the same positions that Aaron, his sons, and the Levites occupied in the Temple (St. Jerome, Letters 146).

• The Church recognizes these offices as three degrees of the Sacrament of Holy Orders: the episcopate (bishops), the presbyterate (elders or priests), and the diaconate (deacons) (CCC 1554-71).