The definitive text is "The Apostolic Origins of Priestly Celibacy" by Christian Cochini. Please read the book before biting on the bitter bait trolled by those adrift from the barque of Peter. The NCR promotes authentic Catholicism as well as the Sierra Club promotes authentic care of the environment
Christian Cichini's book is packed with evidence and real actual Documents. Documents such as the Decretal written by Pope Siricius prior to 400 A.D. In this text, the Pope reminds ALL priests of their DUTY of perpetual continence (celibacy). He reasons the O.T. priests had the requirement to spend their year in the Temple without sexual congress with their wives. The N.T. priests do not sacrifice for just one year. They sacrificed daily; ergo, perpetual celibacy.
Cochini's scholarship is called remarkable. Henri Cardinal de Lubac; "This work is of first importance. It is the result of serious and extensive research. There is nothing even remotely comparable to this work in this whole 20th century"
I have owned my book for YEARS. Buy it yourself and quit the perfidy and ignorance of the NCR
Siricius' Decretal was obviously not the final word on the matter, as Gregory VII had to reaffirm it more forcefully 700 years later by invalidating the marriages of ordained priests.