'The real meaning of celibacy, which today is in general almost totally forgotten but which in the first millennium and beyond was well known, consists in this: complete abstinence in respect to the procreation of children even within the context of marriage. In fact all the first laws written of celibacy speak of this prohibition, that is, of the further procreation of children, a point which we will convincingly document in the second part of this study.
This indicates that, despite the fact that many clerics were already married before their ordination, they were nevertheless held to this particular obligation before they could be ordained. in the beginning, the actual prohibition to marry remained somewhat in the background. It emerged only later when the church imposed this prohibition against marriage on those celibates from whom virtually all the candidates for sacred orders were exclusively recruited.
To complete this initial understanding of celibacy which from the very beginning was correctly termed, “continence”, we must immediately note that married candidates could approach sacred orders only with the consent of their wife. The reason for this lies in the fact that, on the basis of the sacrament that had already been received, the wife had an inalienable right to the use of the valid (and consummated) marriage, which in itself was indissoluble. We will consider the complex problems that resulted from this renunciation in the second part of this work."
'. . . we must begin first with the Council of Elvira. . . . Canon 33 of this Council contained the first regulation on celibacy. . . “It has seemed good absolutely to forbid the bishops, the priests, and the deacons, i.e. all the clerics engaged in service at the altar, to have relations with their wives and procreate children; should anyone do so, let him be excluded from the honor of the clergy.”
. . .the African Council (390). . … Bishop Epigonius. . . says: The rule of continence and chastity had been discussed in a previous council. Let it be taught with more emphasis what are the three ranks that, by virtue of their consecration, are under the same obligation of chastity, i.e. the bishop, the priest and the deacon, and let them be instructed to keep their purity. Bishop Genetlius says: As was previously said, it is fitting that the holy bishops and priests of God as well as the Levites, i.e. those who are in the service of the divine sacraments, observe perfect continence, so that they may obtain in all simplicity what they are asking from God;** what the apostles taught and what antiquity itself observed, let us also endeavor to keep.**
The bishops declared unanimously: It pleases us all that bishop, priest and deacon, guardians of purity, abstain from [conjugal intercourse] with their wives, so that those who serve at the altar may keep a perfect chastity.’
“The Case for Clerical Celibacy”, Alfons Maria Cardinal Stickler
Well I’m a little tired of typing. I recommend if necessary acquiring and referring to the book. It’s slim, inexpensive, easy to read, and full of source citations expressing the continual teaching of the Church.
Of course there’s good source material beyond what it holds too, such as Our Lady speaking to St. Bridget of Sweden on the subject, etc.