Many arguments occur to me which prove that this vice ought not to come under the action of the law.
First of all, the best part of a benefit is lost if the benefit can be sued for at law, as in the case of a loan, or of letting and hiring.
Indeed, the finest part of a benefit is that we have given it without considering whether we shall lose it or not, that we have left all this to the free choice of him who receives it: if I call him before a judge, it begins to be not a benefit, but a loan.
Next, though it is a most honourable thing to show gratitude, it ceases to be honourable if it be forced, for in that case no one will praise a grateful man any more than he praises him who restores the money which was deposited in his keeping, or who pays what he borrowed without the intervention of a judge.
We should therefore spoil the two finest things in human life—a grateful man and a beneficent man; for what is there admirable in one who does not give but merely lends a benefit, or in one who repays it, not because he wishes, but because he is forced to do so?
There is no credit in being grateful, unless it is safe to be ungrateful.
Besides this, all the courts would hardly be enough for the action of this one law.
Who would not plead under it?
Who would not be pleaded against? for everyone exalts his own merits, everyone magnifies even the smallest matters which he has bestowed upon another.
Besides this, those things which form the subject of a judicial inquiry can be distinctly defined, and cannot afford unlimited licence to the judge; wherefore a good cause is in a better position if it be tried before a judge than before an arbitrator, because the words of the law tie down a judge and define certain limits beyond which he may not pass, whereas the conscience of an arbitrator is free and not fettered by any rules, so that he can either give or take away, and can arrange his decision, not according to the precepts of law and justice, but just as his own kindly feeling or compassion may prompt him.
An action for ingratitude would not bind a judge, but would place him in the position of an autocrat.
It cannot be known what or how great a benefit is; all that would be really important would be, how indulgently the judge might interpret it.
No law defines an ungrateful person, often, indeed, one who repays what he has received is ungrateful, and one who has not returned it is grateful.
Even an unpractised judge can give his vote upon some matters; for instance, when the thing to be determined is whether something has or has not been done, when a dispute is terminated by the parties giving written bonds, or when the casting up of accounts decides between the disputants.
When, however, motives have to be guessed at, when matters upon which wisdom alone can decide, are brought into court, they cannot be tried by a judge taken at random from the list of “select judges,”  whom property and the inheritance of an equestrian fortune  has placed upon the roll.