As a part of the same movement, the purely civil marriage of the later Pagan Empire was gradually replaced by religious marriages. There is a manifest propriety in invoking a divine benediction upon an act which forms so important an epoch in life, and the mingling of a religious ceremony impresses a deeper sense of the solemnity of the contract. The essentially religious and even mystical character imparted by Christianity to marriage rendered the consecration peculiarly natural, but it was only very gradually that it came to be looked upon as absolutely necessary. As I have already noticed, it was long dispensed with in the marriage of slaves; and even in the case of freemen, though generally performed, it was not made compulsory till the tenth century.(763) In addition to its primary object of sanctifying marriage, it became in time a powerful instrument in securing the authority of the priesthood, who were able to compel men to submit to the conditions they imposed in the formation of the most important contract of life; and the modern authorisation of civil marriages, by diminishing greatly the power of the Catholic priesthood over domestic life, has been one of the most severe blows ecclesiastical influence has undergone. The absolute sinfulness of divorce was at the same time strenuously maintained by the Councils, which in this, as in many other points, differed widely from the civil law. Constantine restricted it to three cases of crime on the part of the husband, and three on the part of the wife; but the habits of the people were too strong for his enactments, and, after one or two changes in the law, the full latitude of divorce reappeared in the Justinian Code. The Fathers, on the other hand, though they hesitated a little about the case of a divorce which followed an act of adultery on the part of the wife,(764) had no hesitation whatever in pronouncing all other divorces to be criminal, and periods of penitential discipline were imposed upon Christians who availed themselves of the privileges of the civil law.(765) For many centuries this duality of legislation continued. The barbarian laws restricted divorce by imposing severe fines on those who repudiated their wives. Charlemagne pronounced divorce to be criminal, but did not venture to make it penal, and he practised it himself. On the other hand, the Church threatened with excommunication, and in some cases actually launched its thunders against, those who were guilty of it. It was only in the twelfth century that the victory was definitely achieved, and the civil law, adopting the principle of the canon law, prohibited all divorce.(766)