De bono conjugali (“On the Good of Marriage”) was written in response to Jovinian, a monk in Rome who had claimed there was no difference in merit between celibate and married Christians.
In response, in On holy virginity Augustine accorded celibacy a higher status, but now wished to stress that marriage was a good that should be regarded positively. In contrast, the heretical Manichees and even Jerome, Augustine’s Christian contemporary, had denounced marriage.
Augustine begins his defence of marriage by placing it in the social context of God’s creation. He stated that God purposely created two genders of humanity and sexual intercourse so that via this "carnal delight" human society would regenerate and increase in number.
As well as helping to populate the earth, marriage offered companionship and a bond of charity between a man and woman, a legitimate channel for “carnal concupiscence,” and the incentive and obligation of fidelity to one’s marriage bond and to one’s partner.
The final good of marriage is what Augustine calls its sacramentum, which can be freely translated into English as its “sign value." Within this is the indissolubility of a Christian marriage, which symbolises a unity of all who will be subject to God in heaven.
Even so, Augustine still held that spiritual perfection could best be sought in celibacy, and not in marriage.
The call to either, however, was a gift dispensed by God, hence Augustine was comparing the two calls, and not comparing married persons and celibate persons.
For further reading.
Augustine through the Ages: An Encyclopedia.ISBN: 0-8028-3843-X Published in 1999, with 880 pages. Edited by Allan Fitzgerald O.S.A. (Stocks of this publication are now exhausted, but it is still available second-hand online from Amazon.com. and other sites.)
The encyclopedia is the product of more than 140 leading scholars throughout the world. This comprehensive publication contains over 400 articles that cover every aspect of the life and writings of Augustine of Hippo (354-430). It traces his profound influence on the church and the development of Western thought through the past two millennia…."