There is an excellent article in First Things about the nature of celibacy as an essential part of the Church's freedom "to occupy public space on her own terms". In this article Grant Caplan argues that celibacy is indeed much more than a mere discipline, still less, one that arose out of the Middle Ages. It is a very important point which he makes, one which takes the discussion out of the often subjective and parochial arguments which are made against priestly celibacy.
Clerical celibacy, he says, "is a spiritual discipline, and papal primacy a sacred office, that contend with secular power for control of our public reality. They point to a body neither circumscribed by national borders nor resigned to being a disincarnate, “mystical” body floating above time and space. This body, celebrated in the Eucharist, puts national boundaries and loyalties in their proper context."
This article also resonates against the present secular movement which seeks to change the nature of marriage. Secularism seeks to disassociate both the priesthood and marriage from contemporary living and relegate them to an antiquated way of living from which we are now emancipated. This article tells both the Church and secular society that what is at stake is not simply a human endeavour, but a part of God's plan, and that He is the Lord of history.