From consequents:  “If a woman having married a man with whom she had no right of intermarriage, has demanded a divorce, since the children who have been born do not follow their father, the father has no right to keep back any portion of the woman’s dowry.”

From contradictories:  “If the head of a family has left to his wife in reversion after his son the life-interest in the female slaves, and has made no mention of any other reversionary heir, if the son dies, the woman shall not lose her life-interest.  For that which has once been given to any one by will, cannot be taken away from the legatee to whom it has been given without his consent; for it is a contradiction for any one to have a right to receive a thing, and yet to be forced to give it up against his will.”

An argument is derived from efficient causes, in this way:  “All men have a right to add to a common party wall, a wall extending its whole length, either solid or on arches; but if any one in demolishing the common wall should promise to pay for any damages which may arise from his action, he will not be bound to pay for any damage sustained or caused by such arches:  for the damage has been done, not by the party which demolished the common wall, but in consequence of some fault in the work, which was built in such a manner as to be unable to support itself.”

An argument is derived from what has been done, in this way:  “When a woman becomes the wife of a man, everything which has belonged to the woman now becomes the property of the husband under the name of dowry.”

But in the way of comparison there are many kinds of valid arguments; in this way:  “That which is valid in a greater affair, ought to be valid in a less:  so that, if the law does not regulate the limits in the city, still more will it not compel any one to turn off the water in the city.”  Again, on the other hand:  “Whatever is valid in a smaller matter ought to be valid also in a greater one.  One may convert the preceding example.”  Also, “That which is valid in a parallel case ought to be valid in this which is a parallel case.”  As, “Since the usurpation of a farm depends on a term of two years, the law with respect to houses ought to be the same.”  But in the law houses are not mentioned, and so they are supposed to come under the same class as all other things, the property in which is determined by one year’s use.  Equity then must prevail, which requires similar laws in similar cases.[64]

But those arguments which are derived from external circumstances are deduced chiefly from authority.  Therefore the Greeks call argumentations of that kind [Greek:  atechuoi], that is, devoid of art.  As if you were to answer in this way:—­“In the case of some one building a roof for the purpose of covering a common wall, Publius Scaevola asserted that there was no right of carrying that roof so far that the water which ran off it should run on to any part of any building which did not belong to the owner of the roof.  This I affirm to be law.”