35 Although it would be highly instructive to go through the writings of past centuries on ecclesiastical celibacy, this would take so long that We will let a brief account suffice. In Christian antiquity the Fathers and ecclesiastical writers testify to the spread through the East and the West of the voluntary practice of celibacy by sacred ministers (71) because of its profound suitability for their total dedication to the service of Christ and His Church.
Source: Sacerdotalis Caelibatus (Vatican.va)