The presence of seven Roman witnesses was required for the validity of this solemn and deliberate act:  if any adequate provocation had been given by the husband, instead of the delay of two years, he was compelled to refund immediately, or in the space of six months; but if he could arraign the manners of his wife, her guilt or levity was expiated by the loss of the sixth or eighth part of her marriage portion.  The Christian princes were the first who specified the just causes of a private divorce; their institutions, from Constantine to Justinian, appear to fluctuate between the custom of the empire and the wishes of the Church, and the author of the Novels too frequently reforms the jurisprudence of the Code and Pandects.  In the most rigorous laws, a wife was condemned to support a gamester, a drunkard, or a libertine, unless he were guilty of homicide, poison, or sacrilege, in which cases the marriage, as it should seem, might have been dissolved by the hand of the executioner.

But the sacred right of the husband was invariably maintained, to deliver his name and family from the disgrace of adultery:  the list of mortal sins, either male or female, was curtailed and enlarged by successive regulations, and the obstacles of incurable impotence, long absence, and monastic profession were allowed to rescind the matrimonial obligation.  Whoever transgressed the permission of the law was subject to various and heavy penalties.  The woman was stripped of her wealth and ornaments, without excepting the bodkin of her hair:  if the man introduced a new bride into his bed, her fortune might be lawfully seized by the vengeance of his exiled wife.  Forfeiture was sometimes commuted to a fine; the fine was sometimes aggravated by transportation to an island or imprisonment in a monastery; the injured party was released from the bonds of marriage; but the offender during life or a term of years was disabled from the repetition of nuptials.  The successor of Justinian yielded to the prayers of his unhappy subjects, and restored the liberty of divorce by mutual consent:  the civilians were unanimous, the theologians were divided, and the ambiguous word, which contains the precept of Christ, is flexible to any interpretation that the wisdom of a legislator can demand.

The freedom of love and marriage was restrained among the Romans by natural and civil impediments.  An instinct, almost innate and universal, appears to prohibit the incestuous commerce of parents and children in the infinite series of ascending and descending generations.  Concerning the oblique and collateral branches nature is indifferent, reason mute, and custom various and arbitrary.  In Egypt the marriage of brothers and sisters was admitted without scruple or exception:  a Spartan might espouse the daughter of his father, an Athenian that of his mother; and the nuptials of an uncle with his niece were applauded at Athens as a happy union of the dearest relations.