415. The dangers of _epieikeia_ also place limitations on its use. (a) There is the danger that one may be wrong in judging that the lawgiver did not wish to include a case under his law. If this is not certain, one should investigate to the best of one’s ability, and have recourse, if possible, to the legislator or his representative for a declaration or dispensation. It is never lawful to use _epieikeia_ without reasonable certainty that the legislator would not wish the law to apply here and now. (b) There is the danger that one may be in bad faith in deciding that the common good or justice requires the use of _epieikeia_; the motive in reality may be self-interest or escape from obligation, Hence, a person should not use _epieikeia_ except in necessity, when he is thrown on his own resources and must decide for himself; and, even then, he must be sure that he acts from sincerity and disinterestedness. 416. Cases in which the use of _epieikeia_ is lawful are the following: (a) Epieikeia in a wide sense--that is, a benign interpretation made by a private individual that a particular case is not comprehended in the intention of the lawgiver, because the latter had not the power to include it--may be used for all cases in which the opposite interpretation would set the law up in opposition to the common welfare or would work injustice to individuals. Example: The law that goods borrowed must be returned to their owners yields to _epieikeia_, if there is question of putting weapons into the hands of one who would use them against the public security or for the commission of murder; (b) _Epieikeia_ in a strict sense--that is, the judgment that a particular case is not included in the intention of the lawgiver, because the latter had not the wish to include it--may be used for all those cases in which the opposite interpretation would suppose in the lawgiver a severity that is not likely. “The rigor of the law may be extreme injustice” (Cicero, _De Officiis_, I, 10). Example: Titus has the opportunity to make a notable sum of money on a Sunday morning, but cannot make use of the opportunity without missing Mass that day. Caius on a fast day feels well, but is tired and will be not a little inconvenienced if he fasts. Both Titus and Caius may use _epieikeia_, for the Church does not wish to be unkind, nor, generally speaking, to have her laws oblige rigorously and for every case.